JP2023518021A - Improved gas monitoring - Google Patents

Abstract

Disclosed herein are providing a device gas flow having a time-varying parameter to a patient, measuring a parameter of gas present in a composite gas outflow from the patient, determining a parameter of the gas present in the exhalation gas flow using the measured parameter and the time-varying parameter of the gas present in the exhalation gas flow. A method and apparatus for

Description

FIELD OF THE INVENTION The present invention relates to methods and apparatus for determining gas flow parameters exhaled by a patient when using a respiratory apparatus.

BACKGROUND OF THE INVENTION When providing flow assistance/therapy to a patient, clinicians often monitor patient exhaled gas parameters such as _O2 fraction and/or _CO2 fraction. Due to the mix of various flows, the monitored gas parameters often do not truly reflect the actual exhaled gas parameters.

It is an object of the present invention to provide an apparatus and/or method for obtaining estimates of parameters of exhaled gas by a patient.

In one aspect, the present invention provides a method of determining a parameter of gas present in an exhalation gas flow comprising: providing a patient with a device gas flow having a time-varying parameter; and using the measured and time-varying parameters of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow; A method comprising:

In another aspect, the invention provides an apparatus for providing system gas flow and determining parameters of exhaled patient gas flow comprising: a flow source; a sensor for sensing a combined gas outflow; wherein the device provides a device gas flow having a time-varying parameter to determine a parameter of gas present in a composite gas outflow from the patient, the composite gas outflow being a leak from the device gas flow An apparatus comprising a gas flow and an exhalation gas flow from a patient containing gas and configured to determine a parameter of gas present in the exhalation gas flow using the determined gas parameter and the time-varying parameter. may be included.

Optionally, the time-varying parameter is one or more of the flow rate of the device gas flow, or the gas ratio, optionally the gas ratio is a fraction of the gas present in the device gas flow, is the partial pressure of the gas present.

Optionally, the gas ratio is gas fraction, preferably _O2 fraction, or gas partial pressure, preferably _O2 partial pressure.

Optionally, the method or device includes providing device gas flow during an anesthetic procedure.

Optionally, device gas flow is provided through a non-sealing patient interface, preferably a non-sealing cannula.

Optionally, the device gas flow is a high flow gas flow.

Optionally, the method or apparatus further comprises humidifying the apparatus gas flow.

Optionally, using the measured parameters of the gases present in the composite gas outflow to determine the parameters of the gases present in the exhalation gas flow measures only one gas and only the time-varying parameter. and the time-varying parameter is the flow rate.

In another aspect, the present invention provides a method of determining a parameter of gas present in an exhalation gas flow comprising providing a patient with a device gas flow having a time-varying flow rate; determining the parameters of the gas present in the flow, wherein the patient composite gas outflow includes leak gas flow from the device gas flow and exhalation gas flow from the patient including gas; using the determined parameter and the time-varying flow rate of the gas present in the outflow to determine a parameter of the gas present in the exhalation gas flow.

Optionally, the device gas flow having a time-varying flow rate comprises at least a first flow rate at a first time and a second flow rate at a second time, wherein the determined Determining a parameter of the gas present in the exhalation gas flow using the parameter and the time-varying flow rate is determined at the first flow rate and determined at the second flow rate during the combined outflow using the determined parameters of the gas present in the

Optionally, the parameters include fractions of gas components in the exhalation gas flow.

Optionally, the gas is an anesthetic such as _CO2 , _O2 , nitrogen, helium, and/or sevoflurane and/or the sensor detects the following in a combined gas outflow: _CO2 , _O2 , nitrogen , helium, and/or sevoflurane.

Optionally, parameters of gases present in the composite gas outflow are determined during the inspiratory and/or expiratory phases of patient breathing.

［式中、
Ｆ_m（ｔ）、時間ｔにおける、患者複合ガスアウトフロー中で測定されたガス成分の分画
Ｆ_m（ｔ）、時間ｔにおける、患者複合ガスアウトフロー中で測定されたガス成分の分画
Ｑ_o（ｔ）、時間ｔにおける、患者に提供される装置ガスフローの流量（装置ガス流量）、
Ｆ_m（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者複合ガスアウトフロー中で測定されたガス成分の分画（例えば、これは、複合ガスアウトフローの測定されたＣＯ₂、Ｏ₂、窒素、ヘリウム、及び／又はセボフルランなどの麻酔薬分画パラメータ）、
Ｑ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者に提供される装置ガスフローの流量（装置ガスフロー流量）、
Ｆ_o（ｔ）、時間ｔ及びｔ＋Δｔにおける、呼吸装置から来る装置ガスフロー１１’中のガス成分の体積分画、
Ｆ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、呼吸装置から来る装置ガスフロー１１’中のガス成分の体積分画、
Ｑ_oは、装置ガスフローの流量
Ｆ_oは、装置ガスフロー中のガス成分の分画、
Ｆ_Eは、呼出患者ガスフロー中のガス成分の分画］
を使用することを含む。 Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, and using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow, the gas present in the exhalation gas flow is: Determining the fraction of gas (F _E ) is

[In the formula,
F _m (t), the fraction of the gas components measured in the patient combined gas outflow at time t F _m (t), the fraction of the gas components measured in the patient combined gas outflow at time t Q _o (t), the rate of system gas flow provided to the patient at time t (system gas flow rate);
F _m (t + Δt), the fraction of the gas components measured in the patient combined gas outflow at time t + Δt (e.g., this is the measured CO ₂ , O ₂ , nitrogen, helium, and / or anesthetic fractionation parameters such as sevoflurane),
Q _o (t+Δt), the rate of system gas flow provided to the patient at time t+Δt (system gas flow rate);
F _o (t), the volume fraction of the gas components in the system gas flow 11′ coming from the respiratory system at times t and t+Δt;
F _o (t+Δt), the volumetric fraction of the gas component in the system gas flow 11′ coming from the respiratory apparatus at time t+Δt;
Q _o is the flow rate of the system gas flow, F _o is the fraction of the gas components in the system gas flow,
_FE is the fraction of gas components in the exhaled patient gas flow]
including using

Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, and using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow, the gas present in the exhalation gas flow is: Determining the gas fraction (F _E ) is the gas fraction F _E (t),
Q _o (t), Q _o (t + Δt), F _m (t + Δt), F _m (t)
[In the formula,
F _m (t), the volume fraction of gas components measured in the patient combined gas outflow 15 ′ from the patient at time t (which is preferably measured by the sensor 14 combined gas outflow 15 ′ of the measured _CO2 / _O2 fractionation parameters),
F _m (t) is preferably measured at the patient's mouth when the patient's mouth is open and/or at the nose when the patient's mouth is closed;
Q _o (t), the rate of system gas flow 11 ′ provided from the respiratory apparatus to the patient at time t (system gas flow rate);
F _m (t+Δt), the volume fraction of the measured gas constituents in the patient combined gas outflow 15′ at time t+Δt (this is the measured CO ₂ / _O2 fraction parameter), _Fm (t+Δt), is preferably measured in the patient's mouth,
Q _o (t+Δt), the flow rate of the system gas flow 11′ provided from the respiratory apparatus to the patient at time t+Δt (system gas flow rate)]
including determining as a function of

［式中、
Ｆ_E（ｔ）は、呼出患者ガスフロー中のＣＯ₂及び／又はＯ₂濃度（呼気ガスの体積分画）、
Ｆ_m（ｔ）、時間ｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｑ_o（ｔ）、時間ｔにおける、患者に提供される装置ガスフローの流量（装置ガスフロー流量）、
Ｆ_m（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｑ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者に提供される装置ガスフローの流量（装置ガスフロー流量）
Ｑ_oは、装置ガスフローの流量、
Ｆ_Eは、呼出ガスフロー中のガスの分画］
を使用することを含む。 Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, the gas is preferably _CO2 , using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow to determine the gas fraction (F _E ) in the exhaled gas flow as

[In the formula,
F _E (t) is the _CO2 and/or _O2 concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of _CO2 measured in the combined gas outflow at time t;
Q _o (t), the rate of device gas flow provided to the patient at time t (device gas flow rate);
F _m (t+Δt), the fraction of _CO2 measured in the combined gas outflow at time t+Δt;
Q _o (t+Δt), the rate of system gas flow provided to the patient at time t+Δt (system gas flow rate)
Q _o is the flow rate of the device gas flow;
_FE is the fraction of gas in the exhalation gas flow]
including using

Optionally, parameters of gases present in the combined gas outflow from the patient are measured at or near the patient's mouth and/or nose.

Optionally, the first flow rate and the second flow rate are different flow rates.

Optionally, the first flow rate and the second flow rate are high flow rates.

Optionally, the first flow rate and the second flow rate are about 0 L/min or greater, preferably about 20 L/min or greater than about 20 L/min, more preferably about 20 L/min to about 90 L/min.

Optionally, the time-varying flow rate is variable with a varying flow rate of about 0 L/min or greater, preferably about 20 L/min or greater than about 20 L/min, more preferably about 20 L/min to about 90 L/min.

Optionally, the method includes providing device gas flow during the anesthesia procedure.

Optionally, device gas flow is provided through a non-sealing patient interface, preferably a non-sealing cannula.

Optionally, the device gas flow is a high flow gas flow.

Optionally, the method further comprises humidifying the device gas flow.

Optionally, using the measured parameters of the gases present in the composite gas outflow to determine the parameters of the gases present in the exhalation gas flow measures only one gas and only the time-varying parameter. and the time-varying parameter is the flow rate.

In another aspect, the invention provides a method of determining a parameter of gas present in an exhalation gas flow by providing a patient with a device gas flow having a time-varying gas ratio (e.g., gas fraction). and determining the parameters of the gas present in the composite gas outflow from the patient, the patient composite gas outflow being the leak gas flow from the system gas flow and the exhalation gas flow from the patient including the gas. and using the determined parameter and the time-varying gas ratio (e.g., gas fraction) of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow and a method comprising:

Optionally, the device gas flow with time-varying gas fractions includes at least a first gas fraction at a first time and a second gas fraction at a second time, during a combined gas outflow Using the determined parameter of the gas present and the time-varying gas fraction to determine the parameter of the gas present in the exhalation gas flow is determined in the first gas fraction and the second gas fraction. Using the determined parameters of the gases present in the composite outflow determined in the gas fractionation.

Optionally, the parameters include fractions of gas components in the exhalation gas flow.

Optionally, the gas is _CO2 , _O2 , nitrogen, and/or an anesthetic such as helium, sevoflurane.

Optionally, parameters of gases present in the composite gas outflow are determined during the inspiratory and/or expiratory phases of patient breathing.

Optionally, the parameter of the gas present in the exhaled gas flow is the gas fraction, and using the determined parameter of the gas present in the composite gas outflow and the time-varying gas fraction F _E (t), Determining the fraction of gas present in the exhaled gas flow (F _E ) is the gas fraction:
F _o (t), F _o (t + Δt), F _m (t + Δt), F _m (t)
F _E (t) is the CO ₂ and/or O ₂ gas fraction in the exhaled patient gas flow (volume fraction of exhaled gas) at time t;
F _m (t), the fraction of _CO2 measured in the combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the fraction of _CO2 measured in the combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction);
Q _o is the flow rate of the device gas flow;
_FE involves determining as a function of the fraction of gas in the exhaled gas flow.

［式中、
Ｆ_E（ｔ）は、呼出患者ガスフロー中のＣＯ₂及び／又はＯ₂濃度（呼気ガスの体積分画）、
Ｆｍ（ｔ）、時間ｔにおける、複合ガスアウトフロー中の測定されたＣＯ₂及び／又はＯ₂又は他のガスの分画、
Ｆ_o（ｔ）、時間ｔにおける、患者に提供される装置ガスフローのガス分画（装置ガスフローガス分画）、
Ｆ_m（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、複合ガスアウトフロー中の測定されたＣＯ₂及び／又はＯ₂又は他のガスの分画、
Ｆ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者に提供される装置ガスフローのガス分画（装置ガスフローガス分画）、
Ｑ_oは、装置ガスフローの流量、
Ｆ_Eは、呼出ガスフロー中のガスの分画］
を使用することを含む。 Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, the gas is preferably an anesthetic such as _CO2 , _O2 , nitrogen, helium and/or sevoflurane and the combined gas out Determining the gas fraction in the exhaled gas flow using the determined parameter and the time-varying gas fraction of the gas present in the flow includes:

[In the formula,
F _E (t) is the _CO2 and/or _O2 concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
Fm(t), the measured fraction of _CO2 and/or _O2 or other gas in the combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the measured fraction of CO ₂ and/or O ₂ or other gas in the combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction);
Q _o is the flow rate of the device gas flow;
_FE is the fraction of gas in the exhalation gas flow]
including using

Optionally, parameters of gases present in the combined gas outflow from the patient are measured at or near the patient's mouth and/or nose.

Optionally, the first gas fraction and the second gas fraction are different gas fractions.

Optionally, the gas is _O2 and the method comprises the determined _O2 ratio and
_FmCO2 , k, _Qo , _QE
[In the formula,
_FmCO2 is the fraction of _CO2 in the patient combined gas outflow from the patient;
k is the ratio of device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E is the rate of patient exhalation gas flow]
further comprising determining the fraction of _CO2 present in the exhaled gas flow using a function of .

［式中、
Ｆ_mCO2は、患者からの患者複合ガスアウトフロー中のＣＯ₂の分画、
ｋは、患者の口から出る装置ガスフローの比率（及び（１－ｋ）は、鼻を通る比率）、
Ｑ_oは、装置ガスフローの流量、
Ｑ_Eは、患者の呼出ガスフローの流量］
を使用して、呼出ガスフロー中に存在するＣＯ₂比率を決定することを更に含む。 Optionally, the gas is _O2 and the method comprises the determined _O2 ratio and

[In the formula,
_FmCO2 is the fraction of _CO2 in the patient combined gas outflow from the patient;
k is the ratio of device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E is the rate of patient exhalation gas flow]
is used to determine the proportion of _CO2 present in the exhaled gas flow.

Optionally, the gas is _O2 and the method comprises the determined _O2 ratio and
F _mCO2 , F _mO2 , F _EO2 , F _oO2
[In the formula,
_FmCO2 is the fraction of measured _CO2 in the patient combined gas outflow from the patient;
_FmO2 is the fraction of _O2 measured in the patient combined gas outflow from the patient;
F _EO2 is the fraction of O2 in the exhaled patient gas flow F _oO2 is the fraction of O2 in the system gas flow provided to the patient from the respiratory system]
further comprising determining the fraction of _CO2 present in the exhaled gas flow using a function of .

［式中、時間ｔにおいて、
Ｆ_mCO2は、患者からの患者複合ガスアウトフロー中の測定されたＣＯ₂の分画、
Ｆ_mO2は、患者からの患者複合ガスアウトフロー中の測定されたＯ₂の分画、
Ｆ_EO2は、呼出患者ガスフロー中のＯ２の分画、
Ｆ_oO2は、呼吸装置から患者に提供される装置ガスフロー中のＯ２の分画］
を使用して、呼出ガスフロー中に存在するＣＯ₂比率を決定することを更に含む。 Optionally, the gas is _O2 and the method comprises the determined _O2 ratio and

[wherein at time t,
_FmCO2 is the fraction of measured _CO2 in the patient combined gas outflow from the patient;
_FmO2 is the fraction of _O2 measured in the patient combined gas outflow from the patient;
F _EO2 is the fraction of O2 in exhaled patient gas flow;
_FoO2 is the fraction of O2 in the machine gas flow provided to the patient from the respiratory machine]
is used to determine the proportion of _CO2 present in the exhaled gas flow.

In another aspect, the present invention provides an apparatus gas flow and apparatus for determining a parameter of gas present in an exhaled patient gas flow comprising: a flow source; and a controller, the device providing a device gas flow having a time-varying flow rate to determine a parameter of gas present in a composite gas outflow from the patient, the composite gas outflow being controlled by the device Using the determined parameters and time-varying flow rates of the gases present in the composite gas outflow, including leak gas flow from the gas flow and exhalation gas flow from the patient containing gas, present in the exhalation gas flow may include a device configured to determine a parameter of the gas to be used.

Optionally, the device further comprises a humidifier for humidifying the device gas flow.

Optionally, the device further comprises a non-sealing patient interface, preferably a non-sealing nasal cannula, for providing device gas flow to the patient.

Optionally, the device gas flow is a high flow gas flow.

Optionally, the device gas flow having a time-varying flow rate comprises at least a first flow rate at a first time and a second flow rate at a second time, wherein the determined Determining a parameter of the gas present in the exhalation gas flow using the parameter and the time-varying flow rate is determined at the first flow rate and determined at the second flow rate during the combined outflow using the determined parameters of the gas present in the

Optionally, the parameters include fractions of gas components in the exhalation gas flow.

Optionally, the gas is an anesthetic such as _CO2 , _O2 , nitrogen, helium, and/or sevoflurane and/or the sensor detects the following in a combined gas outflow: _CO2 , _O2 , nitrogen , helium, and/or sevoflurane.

Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, and using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow, the gas present in the exhalation gas flow is: Determining the gas fraction (F _E ) is the gas fraction:
Q _o (t), Q _o (t + Δt), F _m (t + Δt), F _m (t)
[In the formula,
F _E (t) is the gas component concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of gas constituents measured in the patient combined gas outflow at time t;
Q _o (t), the rate of system gas flow provided to the patient at time t (system gas flow rate);
F _m (t + Δt), the fraction of the gas component measured in the patient combined gas outflow at time t + ∆t (which is the measured _CO2 / _O2 fraction parameter of the combined gas outflow);
Q _o (t+Δt), the rate of system gas flow provided to the patient at time t+Δt (system gas flow rate)]
including determining as a function of

［式中、
Ｆ_E（ｔ）は、呼出患者ガスフロー中のＣＯ₂又はＯ₂又は他のガス分画（呼気ガスの体積分画）、
Ｆ_m（ｔ）、時間ｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｑ_o（ｔ）、時間ｔにおける、患者に提供される装置ガスフローの流量（装置ガスフロー流量）、
Ｆ_m（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｑ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者に提供される装置ガスフローの流量（装置ガスフロー流量）、
Ｑ_oは、装置ガスフローの流量、
Ｆ_Eは、呼出ガスフロー中のガスの分画］
を使用することを含む。 Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, the gas is preferably _CO2 , the determined parameter (F _E ) of the gas present in the combined gas outflow and the time Using the change flow rate to determine the gas fraction in the exhalation gas flow is

[In the formula,
F _E (t) is the _CO2 or _O2 or other gas fraction in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of _CO2 measured in the combined gas outflow at time t;
Q _o (t), the rate of device gas flow provided to the patient at time t (device gas flow rate);
F _m (t+Δt), the fraction of _CO2 measured in the combined gas outflow at time t+Δt;
Q _o (t+Δt), the rate of system gas flow provided to the patient at time t+Δt (system gas flow rate);
Q _o is the flow rate of the device gas flow;
_FE is the fraction of gas in the exhaled gas flow]
including using

Optionally, the sensor is arranged to measure parameters of gases present in the combined gas outflow from the patient at or near the patient's mouth and/or nose.

In another aspect, the present invention provides an apparatus gas flow and apparatus for determining a parameter of gas present in an exhaled patient gas flow comprising: a flow source; and a controller, wherein the device provides a device gas flow having a time-varying gas ratio (e.g., gas fraction) to determine a parameter of gas present in the combined gas outflow from the patient. , the composite gas outflow includes the leak gas flow from the device gas flow and the exhaled gas flow from the patient containing gas, and the determined parameters and time-varying gas ratios of the gases present in the composite gas outflow (e.g. , gas fractionation) to determine parameters of gases present in the exhaled gas flow.

Optionally, the device gas flow with time-varying gas fractions includes at least a first gas fraction at a first time and a second gas fraction at a second time, during a combined gas outflow Using the determined parameter of the gas present and the time-varying gas fraction to determine the parameter of the gas present in the exhalation gas flow is determined in the first gas fraction and the second gas fraction. Using the determined parameters of the gases present in the composite outflow determined in the gas fractionation.

Optionally, the parameters include fractions of gas components in the exhalation gas flow.

Optionally, the gas is _CO2 , _O2 , nitrogen, helium, and/or an anesthetic such as sevoflurane.

Optionally, the parameter of the gas present in the exhalation gas flow is a gas fraction, and using the determined parameter and the time-varying gas fraction of the gas present in the composite gas outflow, Determining the fraction of gas present (F _E ) is the gas fraction:
F, F _o (t + Δt), F _m (t + Δt), F _m (t)
where F _E (t) is the gas component concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of gas constituents measured in the patient combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t + Δt), the fraction of the gas components measured in the patient combined gas outflow (which is the measured _CO2 / _O2 fraction parameter of the combined gas outflow) at time t + ∆t;
_Fo (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction)
including determining as a function of

式中
Ｆ_E（ｔ）は、時間ｔにおける、呼出患者ガスフロー中のＣＯ₂又はＯ₂又は他のガス（呼気ガスの体積分画）、
Ｆ_m（ｔ）、時間ｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｆ_o（ｔ）、時間ｔにおける、患者に提供される装置ガスフローのガス分画（装置ガスフローガス分画）、
Ｆ_m（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、複合ガスアウトフロー中で測定されたＣＯ₂の分画、
Ｆ_o（ｔ＋Δｔ）、時間ｔ＋Δｔにおける、患者に提供される装置ガスフローのガス分画（装置ガスフローガス分画）、
Ｑ_oは、装置ガスフローの流量、
Ｆ_Eは、呼出ガスフロー中のガスの分画
を使用することを含む。 Optionally, the parameter of the gas present in the exhalation gas flow is the gas fraction, the gas is preferably an anesthetic such as _CO2 , _O2 , nitrogen, helium and/or sevoflurane and the combined gas out Determining the gas fraction (F _E ) in the exhaled gas flow using the determined parameters and the time-varying gas fraction of the gas present in the flow:

where F _E (t) is the CO ₂ or O ₂ or other gas in the exhaled patient gas flow (volume fraction of exhaled gas) at time t;
F _m (t), the fraction of _CO2 measured in the combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the fraction of _CO2 measured in the combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction);
Q _o is the flow rate of the device gas flow;
_FE involves using a fraction of the gas in the exhalation gas flow.

Optionally, the sensor is arranged to measure parameters of gases present in the combined gas outflow from the patient at or near the patient's mouth and/or nose.

In another aspect, the present invention provides a method for determining the _O2 and/or _CO2 fraction present in exhaled gas flow, comprising a humidified high-flow device gas flow having a time-varying flow rate through an unsealed nose. providing a patient via a cannula; measuring a fraction of _O2 and/or _CO2 present in a combined gas outflow from the patient; measuring O2 present in the combined gas outflow; Determining the fraction _O2 and _{/or CO2 present in the exhaled gas flow using the fraction of 2 or the} fraction of CO2 and the time-varying flow rate.

In another aspect, the invention, when performed in one or more processing devices, provides a patient with an apparatus gas flow having a time-varying parameter to the one or more processing devices; measuring a parameter of the gas present in the gas outflow and using the measured parameter and the time-varying parameter of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow; A non-transitory computer-readable medium having computer-executable instructions stored thereon for performing a method of determining a parameter of gas present in the exhale gas flow, including determining.

In another aspect, the present invention provides a method of determining a parameter of exhaled patient gas flow comprising providing a patient with a device gas flow having a time-varying parameter; Determining, the composite gas outflow includes the leak gas flow from the device gas flow and the exhaled patient gas flow including gas constituents, and the determined parameters of the composite gas outflow are: and using the determined and time-varying parameters of the composite gas outflow to determine the proportion of gas present in the exhalation gas flow can be

optionally, the sensor is the patient's mouth and nose;
Composite gas flows are sensed by sensing oral or nasal gas flows.

In another aspect, the present invention provides a method of determining the _CO2 fraction present in the exhalation gas flow comprising providing a patient with a high flow device gas flow and determining the fraction of ₂ and the determined _O2 ratio and
_FmCO2 , k, _{Qo , QE}
during the ceremony
F _{m CO2} is the volume fraction of _CO2 in the device gas flow;
k is the ratio of device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E uses a function of the patient's exhaled gas flow rate to determine the CO ₂ fraction present in the exhaled gas flow;
A method comprising:

式中
Ｆ_mＣＯ₂は、装置ガスフローのＣＯ₂の体積分画、
ｋは、患者の口から出る装置ガスフローの比率（及び（１－ｋ）は、鼻を通る比率）、
Ｑ_oは、装置ガスフローの流量、
Ｑ_Eは、患者の呼出ガスフローの流量
を使用して、呼出ガスフロー中に存在するＣＯ₂比率を決定することと、
を含む方法を含むものとされ得る。 In another aspect, the present invention provides a method of determining the _CO2 fraction present in the exhalation gas flow comprising providing a patient with a high flow device gas flow and determining the fraction of ₂ and the determined _O2 ratio and

where F _{m CO2} is the volume fraction of _CO2 in the device gas flow;
k is the ratio of device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E uses the patient's exhalation gas flow rate to determine the CO ₂ fraction present in the exhalation gas flow;
A method comprising:

References to numerical ranges disclosed herein (eg, 1 to 10) include all rational numbers within that range (eg, 1, 1.1, 2, 3, 3.9, 4, 5, 6, 6.5, 7, 8, 9, and 10), and also any range of rational numbers therein (eg, 2-8, 1.5-5.5, and 3.1-4. 7) is also incorporated, and thus all subranges of all ranges expressly disclosed herein are hereby expressly disclosed. These are only examples of what is specifically intended, and all possible combinations of numerical values between the lowest and highest values recited are deemed to be expressly included in this application as well.

As used herein, the term "comprising" means "consisting at least in part of." When interpreting each statement in this specification that includes the term "comprising," features other than those prefaced by the term may also be present. Related terms such as "comprise" and "comprises" are to be interpreted similarly. Throughout the specification and claims, unless clearly required by the context, the words "comprise," "comprising," etc. are used in shall be interpreted in an inclusive sense, ie, in the sense of "including, but not limited to."

The phrase "computer-readable medium" shall be construed to include a single medium or multiple media. Examples of multiple media include centralized or distributed databases and/or associated caches. These multiple media store one or more sets of computer-executable instructions. The phrase "computer-readable medium" is also capable of storing, encoding, or carrying a set of instructions for execution by a processor of a computing device and any of the methods described herein. It should be construed to include any medium that causes a processor to implement one or more of them. Computer-readable media may also store, encode, or carry data structures used by or associated with these instruction sets. The phrase "computer-readable medium" includes solid-state memory, optical media, and magnetic media.

When references are made herein to patent specifications, other external documents, or other sources of information, this is generally to provide a context for discussing the features of the disclosure. Unless otherwise specified, reference to such external documents does not imply that such documents or such sources are prior art or form part of the common general knowledge in the art in any jurisdiction. should not be construed as an endorsement of

The invention also extends broadly to the parts, elements and features individually or collectively referred to or shown in the specification of this application, in any combination of two or more of the parts, elements or features in whole or in part. may be configured. When the foregoing description refers to integers or components having known equivalents thereof, those integers are incorporated herein as if individually set forth.

Many changes in structure and widely different embodiments and applications of the invention will occur to those skilled in the art to which this invention pertains without departing from the scope of the invention as defined in the appended claims. be. The present disclosure and descriptions herein are purely illustrative and are not intended to be limiting in any way. Where specific integers are referred to herein as having known equivalents in the art to which this invention pertains, such known equivalents are incorporated herein as if set forth individually. It is considered to be The invention consists of the foregoing and also envisages constructions of which the following are merely examples.

Embodiments are described with reference to the following drawings.

Figure 3 shows the flow between the respiratory apparatus, the patient, and the patient's environment. A respiratory device for providing high flow. 2 is a trace of CO2 fraction during combined and exhaled gas flows; Figure 3 shows the components of the device gas flow (time-varying flow rate) and the combined composite gas outflow. 4 shows an alternative device gas flow; 4 shows an alternative device gas flow; 1 is an embodiment of a respiratory apparatus implementing a time-varying apparatus flow and estimating exhaled gas parameters; 1 is one embodiment of a method performed by a respiratory apparatus to estimate time-varying flow gas flow and exhaled gas parameters; The components of the device gas flow (time-varying gas fraction) and the combined combined gas outflow are shown. 4 shows an alternative device gas flow; 4 shows an alternative device gas flow; FIG. 11 is one embodiment of a method performed by a breathing apparatus to estimate time-varying gas fractionator gas flow and exhaled gas parameters; FIG. Various gas flows in and out of the patient are shown.

Detailed Description 1. Overview The present embodiments are designed to provide exhaled gas flow by a patient ("exhaled gas flow") when using a respiratory apparatus that provides a (preferably high) flow rate through a non-sealing patient interface, e.g., a non-sealing nasal cannula. ”) for determining gas parameters. ("Determining a gas parameter" can mean determining, obtaining, or otherwise obtaining an estimate, value, indication, or other information of or relating to a gas parameter. but not limited to)

The described embodiments provide apparatus and methods for determining a parameter of exhalation gas flow by a patient, where the parameter is a ratio of gas components in an exhalation gas flow comprising two or more constituent gas components (e.g., concentration/fraction or partial pressure). In certain situations, the patient is breathing spontaneously (ie, breathing under his or her own efforts, even if the breathing is shallow or depressed). For example, the exhaled gas flow may include _O2 , _CO2 , nitrogen, helium, anesthetics (such as sevoflurane), etc., and the parameter is the proportion of _CO2 in the exhaled gas flow from the patient (e.g., concentration/fraction or partial pressure) or O ₂ ratio (eg concentration/fraction or partial pressure). Here, the gas component is _CO2 or _O2 and the parameter is the ratio of the gas components that make up the exhalation gas flow. In some embodiments, the parameters may relate to gases other than _CO2 or _O2 .

A medical professional may wish to obtain an estimate of exhaled gas flow parameters, for example, when monitoring a patient during a medical procedure. Medical procedures should be considered broadly, administration of sedatives and/or anesthetics during surgical procedures, oxygenation and pre-oxygenation phases or procedures, or at any other time without limitation. any time before, during, or after sedation or anesthesia (sedation and anesthesia are more commonly referred to herein as "anesthetic procedures"), including pre- and post-operative procedures, including Medical treatment may also include providing respiratory assistance, such as high-flow respiratory assistance.In the context of the present specification, medical treatment may also include any aspect of the provision of a particular treatment to a patient. The described embodiments are not limited to use only in medical procedures, the described embodiments may be used in an ICU or any hospital where respiratory support is provided. It can be used in other situations.

References to "exhale" may be used interchangeably herein with "expire."

As used herein, references to "proportion" in the context of gases refer to any relative measure of constituent gas components in a total gas containing two or more constituent gas components. For example, ratios can include:
・Volume fractionation,
・fractionation,
・Volume concentration,
·concentration,
・Molarity,
・Partial pressure

The ratio measured can be a parameter measured by the sensor used, whether it is concentration, fraction, partial pressure, or other. The determined ratio may be a parameter desired by a user and/or processed by a component of the respiratory system or associated with the respiratory system.

References herein to "concentration" may also be referred to as "fraction", whether it is the breath gas flow, the device flow, or any other flow. It can be expressed as the volume ratio of the gas of interest to the volume of the overall constituent gas in the medium. However, the parameter can be measured differently and the gas can be different. These are just examples.

The gas associated with the determined gas parameter may be, but is not limited to, oxygen ( _O2 ), carbon dioxide ( _CO2 ), nitrogen (N), helium (He), or sevoflurane. It will be understood that when specific gases are referred to herein, this is merely an example and the discussion may apply to any gas, not just those mentioned.

As used herein, "high flow" is any gas flow that has a normal/higher than normal flow rate, e.g., higher than the normal inspiratory flow rate of a healthy patient means. This may be provided by a non-sealing patient interface, such as a non-sealing breathing system where significant leakage occurs at the entrance to the patient's airway due to the non-sealing prongs. Humidification is also provided to improve patient comfort, compliance and safety. Alternatively or additionally, this may be higher than the otherwise contextually relevant threshold flow rate. For example, when providing gas flow to a patient at a rate that meets inspiratory demand, that rate may be considered "high flow" because it is higher than the nominal rate that may have been provided. . Thus, "high flow" is context dependent and what constitutes "high flow" depends on the health status of the patient, the type of treatment/treatment/assistance provided, the nature of the patient (large, small, adult, pediatric). ), etc. A person skilled in the art knows from the context what constitutes "high flow". This is the magnitude of flow over and above what could have been provided.

However, without limitation, some indications of high flow rate may be as follows.
delivery of gas to the patient at a flow rate of about 5 or 10 liters/minute (5 or 10 LPM or L/min) or greater, in some configurations about 5 or 10 LPM to about 150 LPM or about 15 LPM to about 95 LPM, or about 20 LPM to about 90 LPM, or about 25 LPM to about 85 LPM, or about 30 LPM to about 80 LPM, or about 35 LPM to about 75 LPM, or about 40 LPM to about 70 LPM, or about 45 LPM to about 65 LPM, or Delivery of gas to the patient at a flow rate of about 50 LPM to about 60 LPM. For example, according to these various embodiments and configurations described herein, the flow rate of gas supplied or provided to the interface through the system or from the flow source is at least about 5, 10, 20 , 30, 40, 50, 60, 70, 80, 90, 100, 110, 120, 130, 140, 150 LPM, or more flows, and the effective range is any of these values (e.g., about 20 LPM to about 90 LPM, about 40 LPM to about 70 LPM, about 40 LPM to about 80 LPM, about 50 LPM to about 80 LPM, about 60 LPM to about 80 LPM, about 70 LPM to about 100 LPM, about 70 LPM to about 80 LPM ).

At "high flow", the gas delivered is selected, for example, depending on the therapeutic application. The delivered gas may contain a proportion of oxygen. In some configurations, the percentage of oxygen in the gas delivered is from about 15% to about 100%, from about 20% to about 100%, or from about 21% to about 100%, or from about 30% to about 100%. , or about 40% to about 100%, or about 50% to about 100%, or about 60% to about 100%, or about 70% to about 100%, or about 80% to about 100%, or about 90% can be to about 100%, or about 100%, or 100%.

In some embodiments, the delivered gas may contain a proportion of carbon dioxide. In some configurations, the percentage of carbon dioxide in the gas delivered is greater than 0%, about 0.3% to about 100%, about 1% to about 100%, about 5% to about 100%, about 10% % to about 100%, about 20% to about 100%, or about 30% to about 100%, or about 40% to about 100%, or about 50% to about 100%, or about 60% to about 100%, or about 70% to about 100%, or about 80% to about 100%, or about 90% to about 100%, or about 100%, or 100%.

The "high flow" flow rate for premature infants/infants/children (with body masses ranging from about 1 to about 30 kg) can be different. The therapeutic flow rate can be set between 0.4-0.8 L/min/kg with a minimum of about 0.5 L/min and a maximum of about 25 L/min. For patients under 2 kg, the maximum flow is set at 8 L/min.

The variable flow is set at 0.05-2 L/min/kg with a preferred range of 0.1-1 L/min/kg and another preferred range of 0.2-0.8 L/min/kg.

The therapeutic flow rate can be time-varying (eg, fluctuating). That is, therapeutic flow may have a time-varying (eg, fluctuating) flow component. This time-varying flow rate can assist in therapy.

Note that embodiments herein also have a time-varying (eg, fluctuating) signature flow rate, which may be in addition to the therapeutic flow rate. Thus, when therapeutic time-varying flow is used, the gas flow from the device has a therapeutic time-varying gas flow component (portion) and a signature time-varying flow component (portion). The therapeutic time-varying flow has a different purpose than the signature time-varying flow and can be of different frequency and/or amplitude (but they can overlap or be the same). The signature flow rate can be lower than, the same as, or higher than the therapeutic flow rate. The signature flow frequency can be lower than, the same as, or higher than the therapeutic flow frequency (if time varying). In some embodiments, the signature flow has a higher frequency than the therapeutic flow. Therapeutic time-varying flow provides respiratory support, airway clearance, oxygenation, etc., while signature time-varying flow assists in determining gas parameters. Signature time-varying flow is described in more detail below. Throughout the specification, unless stated otherwise, the focus will be on the time-varying flow rate, which excludes the possibility that there may also be a therapeutic time-varying flow rate for therapeutic reasons. isn't it.

As an example, the signature flow rate can be stepped between a first flow rate and a second flow rate, one or both of which can be within a range of approximately 0 LPM to 70 LPM. The maximum signature flow rate can be the therapeutic flow rate. The signature flow rate may be combined with (eg, added to) the therapeutic flow rate, or may form part or all of the therapeutic flow rate. That is, the therapeutic flow rate itself can be the signature flow rate. In some embodiments, signature flow rate may be related to therapeutic flow rate as a percentage. For example, the signature time-varying flow rate (adult) is
- from about 0% to about 200% of the therapeutic flux;
- about 0% to 100% of the therapeutic flux,
from about 100% to 200% of therapeutic flux, or from about 50% to 150% of therapeutic flux,
within the range of
and/or from about 0 to 140 LPM,
・Approximately 0 to 70 LPM,
・Approximately 70 to 140 LPM,
・About 40 to 100LPM, or ・About 20 to 60LPM
is within the range of

Note also that these are not limiting flows and the signature flow can be negative, but when combined with the therapeutic flow results in a positive total flow.

High flow rates have been found to be effective in meeting or exceeding the patient's normal real inspiratory flow, increasing the patient's oxygenation, and/or reducing the work of breathing. Furthermore, the high flow rate can produce a flushing effect on the nasopharynx such that the anatomical dead space of the upper airway is flushed by the high flow rate of incoming gas flow. This creates a reservoir of fresh gas available for each breath while minimizing rebreathing of carbon dioxide, nitrogen, etc.

By way of example, a high flow breathing apparatus 10 is described, eg, with reference to FIGS. 1A and 1B. Generally, the apparatus includes a flow generator 50 in the form of a motor/impeller arrangement, an optional humidifier 52, a controller 19, and a user input/output interface (eg, including a display and input devices such as buttons, touch screens, etc.). includes a main housing 10 enclosing a The controller 19 operates the flow generator to generate a flow of gas (gas flow) for delivery to the patient, operates the humidifier (if present) to humidify and/or humidify the generated gas flow. device, including heating, receiving user input from a user interface for reconfiguring and/or user-defined operation of the device, and outputting information to the user (e.g., on a display). Configured or programmed to control components. The user may be a patient, medical personnel, or anyone else interested in using the device. The patient breathing conduit is coupled to the gas flow output of the flow therapy device housing and to a patient interface 51, such as a manifold and a nasal cannula with nasal prongs. The patient breathing conduit may have heater wires 5 for heating the gas flow delivered to the patient.

High flow rates can be used as a means to enhance gas exchange and/or respiratory support by delivering oxygen and/or other gases and by removing _CO2 from the patient's airways. High flow rates can be particularly useful before, during, or after medical procedures.

Further benefits of high gas flow include that high gas flow increases pressure within the patient's airways, thereby providing pressure support to open the airways, trachea, lungs/alveoli, and bronchioles. obtain. Opening these structures enhances oxygenation and assists _CO2 removal to some extent.

Increased pressure can also keep structures such as the larynx from obstructing viewing of the vocal cords during intubation. When humidified, high gas flow also prevents airway drying, reduces mucociliary damage, and reduces the risk of laryngeal spasm as well as epistaxis, aspiration (as a result of nosebleeds), and airway obstruction, swelling and bleeding. It can reduce the risks associated with dry airways such as Another advantage of high gas flow is that the flow can remove smoke generated during surgery in the airways. For example, smoke may be produced by lasers and/or ablation devices.

Referring to FIG. 1A, this embodiment can be used in any suitable manner in which gas flow is provided from respiratory apparatus 10 to a patient to provide therapy (such as, but not limited to, high flow gas flow for high flow therapy). can be used in difficult situations. Apparatus 10 provides apparatus gas flow 11 . This device gas flow 11 has a flow rate. The flow rate can be constant (ie, does not change over time) or can vary over time, depending on the requirements of the therapy. In these situations, the patient inhales at least a portion of system gas flow 11 and exhales gas flow 13, which has constituent gas components such as _CO2 , _O2 , nitrogen, helium, and the like. The exhalation gas flow 13 may also contain an anesthetic such as sevoflurane.

It is useful for medical professionals to determine exhaled patient gas flow 13 (eg, as measured by sensor 14, etc.) when monitoring a patient. In particular, it is useful for medical professionals to determine parameters of the constituent gas constituents of the patient's exhaled gas flow 13, such as the ratios (eg, fractions) of _CO2 or _O2 . This may indicate how the patient is responding to therapy, the patient's overall comfort, and/or if the patient is undergoing medical treatment, when the next phase of medical treatment may begin. useful for evaluating For example, when pre-oxygenating a patient, measuring the _O2 fraction in the exhaled gas flow 13 helps determine whether pre-oxygenation has been achieved. As another example, measuring the _CO2 fraction helps determine whether a patient is breathing. However, when device gas flow 11 is provided to the patient, determining the parameters of the gas components of exhalation gas flow 13 (whether it is _O2 fraction, _CO2 fraction, or other gas parameters) is It can be difficult. Because the leak (“leak gas flow”) 12 from the device gas flow 11 from the respiratory device 10 is added to the exhalation gas flow 13 to result in the total gas outflow from the patient (“composite gas flow”) as measured by sensor 14, for example. outflow") 15 occurs.

"Leak gas flow" 12 includes excess gas flow from device gas flow 11 that is not inhaled by the patient and/or does not enter the patient's lower respiratory tract and leaks into the environment through the mouth and/or nose.

A “combined gas outflow” is a combination of the leak gas flow 12 and the breath gas flow 13 . Therefore, exhalation gas flow 13 is not actually measured, but rather a composite gas outflow 15 comprising a combination of leak flow 12 and the patient's exhalation gas flow. The leak gas flow 12 dilutes (eg when measuring the _CO2 fraction) or increases (eg when measuring the _O2 fraction) the gas constituents of the exhalation gas flow 13 measured by the sensor 14. or, more generally, may "change" and provide misleading information regarding the parameters of the resulting gas composition. This phenomenon is exacerbated at high flow rates, for example when providing high flow therapy. So, instead of measuring the breath gas flow 13, the sensor measures the gas components of the combined gas outflow 15, which includes the breath gas flow 13 and possibly at least a portion of the system gas flow 11 (i.e. the leak gas flow 12). is actually measured. The apparent reading of the breath gas flow is inaccurate because the breath gas flow 13 is not actually measured, but rather the composite gas outflow is measured. Note that the composite gas outflow 15 may also include other gases, such as those present in the ambient air.

Exhalation gas flow 13, leak gas flow 12, and combined gas outflow 15 can exit the mouth, nose, or mouth and/or nose. Several situations exist. 1) The patient's mouth is open and the exhaled gas flow, leak gas flow, and thus the combined combined gas outflow, primarily (which may include completely) exit the patient's mouth. 2) The patient's mouth is open and exhaled gas flow, leak gas flow, and thus the combined combined gas outflow exit both the patient's mouth and nose. 3) The patient's mouth is closed and exhalation gas flow, leak gas flow and thus the combined combined gas outflow exits the patient's nose. When measuring the combined gas outflow 15, this can be done by suitable sensors arranged to measure either the flow out of the mouth, the flow out of the nose, or the flow out of the nose and mouth. If the sensor measures only the flow out of the mouth or only the flow out of the nose, the sensor may not measure the total combined gas outflow. This is because some may also exit the other hole (eg, the other nose or mouth, depending on which one the sensor is not measuring). In this case, the sensor measurements are still relevant and/or sufficient measurements of the combined gas outflow are obtained for determining the gas parameters of the exhalation gas flow.

As an example, FIG. 2 shows a patient's exhaled _CO2 fraction measurements. FIG. 2 shows an exemplary carbon dioxide signal comparing the true _CO2 waveform (solid line) X and the measured diluted waveform (dotted line) X ^* . It can be seen that in this setup both the amplitude and shape of the waveform that can be displayed to the medical professional are affected by the dilution of the system gas flow 11 . This information indicates to the medical professional that gas exchange is occurring, but from an accurate reading of the amplitude and shape of the waveform (e.g., the patient's end-tidal CO ₂ (carbon dioxide released by the patient at the end of expiration)). It negates the additional insight of the health care professional that can be gained from knowing the level of This information may be useful to know during anesthetic procedures such as procedural sedation when the patient may be breathing shallowly. The actual measured waveform (which is effectively a measurement of the composite gas outflow 15) is shown by the dashed line X ^* . However, this is a misleading waveform. This is because the actual/true CO ₂ ratio (in this case fraction) of the exhaled gas flow 13 is higher as indicated by the solid line X. The measured waveform is low because it actually measures the CO ₂ fraction in the sum of leak gas flow 12 and exhale gas flow 13 added together to form composite gas outflow 15 . The _CO2 fraction in the exhaled gas flow will actually be higher, _but the measured _CO2 Fractions are diluted. In some cases, the dilution can be so pronounced that the _CO2 signal can sometimes be quite difficult to detect. For example, if the patient has shallow breathing and a high flow is provided to the patient. Although X ^* is an accurate measurement, it does not truly reflect the _CO2 fraction X of the exhaled gas flow 13', but rather a measurement of the _CO2 fraction X ^* in the combined gas outflow 15'. Note that the value

A similar situation can be assumed in measuring the O ₂ fraction of the exhaled gas flow 13 . Leak gas flow 12 increases the O ₂ fraction of combined gas outflow 15 when the O ₂ fraction of patient exhalation is less than the O ₂ fraction provided by the respiratory apparatus, thus increasing the actual exhalation gas flow 13 . resulting in a misleading representation of the _O2 fraction of

This embodiment relates to a non-sealed breathing apparatus that preferably provides a high flow rate of gas to a patient. An unsealed device means that some of the gas flow is not inhaled by the patient, but rather "leaks" into the surroundings (leak flow 12). Embodiments measure the parameters of the gas constituents in the combined gas outflow 15 at or near the patient (“near”) and take into account the effect of the leak gas flow 12 on the parameter measurements, which by adjusting the measurements (or otherwise using the measurements and other information) and determining the parameters of the desired gas constituents in the actual exhaled gas flow 13 from the patient. Apparatus and methods are provided for determining actual exhaled gas flow 13 parameters of gas constituents. Device gas flows can be varied by signatures to aid in parameter determination. Note that the combined gas outflow 15 may also include other gases (in addition to _CO2 and _O2 ), such as those present in ambient air. This embodiment describes work in the presence of such additional gases.

A respiratory device may include a flow source capable of providing a flow of device gas to a patient. The device provides a time-varying device gas flow such that the time-varying parameter of the device gas flow changes over time. This provides a signature that can be used to assist in determining the gas parameters of the actual exhaled gas flow 13 . As possible examples, the time-varying parameters of the device gas flow can be flow rates or gas ratios, such as gas fractions (eg _O2 fractions) and/or gas partial pressures (eg _O2 partial pressures).

In one embodiment, the flow source provides a time varying device gas flow having a time varying flow rate. In another embodiment, the flow source provides a time varying device gas flow having a time varying gas ratio (such as gas fraction or gas partial pressure). The flow source may be capable of providing gas flow to the patient at two or more flow rates or two or more gas ratios. The flow source varies the flow rate provided to the patient, e.g. )be able to. When varying between two or more gas ratios, preferably the flow rate is not varied by the signature flow rate and only the therapeutic component is provided without any non-therapeutic flow rate changes being applied.

The breathing apparatus includes one or more sensors for measuring desired gas parameters at two or more flow rates and/or two or more gas ratios and a controller for determining exhaled patient gas flow 13 parameters. can contain. If a target gas, eg O ₂ , is delivered to the patient, the respiratory apparatus may include an input to control the concentration/fraction or partial pressure of the target gas in the delivered gas flow. The input can be manual (eg, flow meter dial) or electronic. Reference herein to a controller configured to perform a function can also mean one or more controllers configured to perform such function, and reference to a controller should not be considered a limitation of the physical equipment used. A non-transitory computer-readable medium storing a program for performing the method on the controller may be provided.

In one embodiment, the gas flow is provided to the patient at first and second gas flow rates or time-varying (eg, varying) flow rates (continuously or discontinuously to create multiple gas flow rates). ) is provided (having at least first and second gas flow rates). This is the signature time-varying gas flow rate. As noted above, the time varying gas flow can also have a therapeutic time varying gas flow portion (as well as a signature time varying gas flow portion). For purposes of illustration, embodiments herein are described with reference to only signature time-varying flow portions, but the flow also has a therapeutic time-varying portion (or the therapeutic portion also doubles as a signature time-varying portion). form a secondary purpose) is not excluded. Thereafter, the gas parameter (of the target gas) (i.e., the gas parameter of the composite gas outflow 15) is set at the time of the first flow rate and at the time of the second flow rate (or, if changing, the second of the multiple gas flows). 1 and 2) are measured at the patient. Using, for example, Equation 4, the first and second gas flow rates and the gas parameters measured at each time are used to determine exhalation gas parameters (ie gas parameters of exhalation gas flow 13). This process can then be repeated over a period of time and the determined exhaled gas parameters can be extrapolated and presented as a signal. It should be noted that in embodiments, the gas parameter measurements may be received indirectly by the controller via user interface input from the user, rather than directly from the sensors.

Alternatively, in another embodiment, the gas flow is a first and second gas ratio (e.g., the fraction of oxygen in the device gas flow 11 may be varied) or a changing (e.g., fluctuating) gas ratio (which varies continuously or discontinuously to create multiple gas ratios) is provided to the patient. The gas parameter (of the target gas) is then set to the time of the first gas fraction and the time of the second gas fraction (or, if varying, the time of the first and second gas ratios of the multiple gas ratios). ii) is measured in the patient. First and second gas fractions or varying (eg, varying) fractions are provided (having at least a first gas fraction and a second gas fraction). The gas parameters in the first and second fractions are then measured, and the measured gas parameters at each time are used to determine exhaled gas parameters, eg, using Equation 4. This process can then be repeated over a period of time and the determined exhaled gas parameters can be extrapolated and presented as a signal. This approach is particularly suitable for gases commonly administered to patients (eg oxygen). Note that in embodiments, the gas parameter measurements may be received indirectly by the controller via user interface input from the user, rather than directly from the sensors.

Alternatively, in another embodiment, gas flows are provided to the patient at first and second gas ratios (eg, oxygen partial pressure in system gas flow 11 may be varied). Gas parameters are then measured in the patient at the first gas partial pressure and at the second gas partial pressure. First and second gas partial pressures or varying (eg, varying) partial pressures are provided (having at least first and second gas partial pressures). The gas parameters (of the target gas) at the first and second partial pressures are then measured, and the measured gas parameters at each time are used to determine exhaled gas parameters, eg, using Equation 4. This process can then be repeated over a period of time and the determined exhaled gas parameters can be extrapolated and presented as a signal. This approach is particularly suitable for gases commonly administered to patients (eg oxygen). It should be noted that in embodiments, rather than the controller receiving gas parameter measurements directly from the sensors, the controller may receive the measurements indirectly via user interface input from the user.

Note that "at" does not have to be temporally precise, it can mean "approximately", and small time differences do not change the validity of the measurement. . Also, if the device changes the gas flow rate or gas ratio (e.g., gas fraction or gas partial pressure), due to the distance the gas flow must travel (within the device, conduit, and patient interface) , there may be a delay between the change in the flow/gas ratio in the breathing device 10 and the arrival of the new flow/gas ratio to the patient. Also, when sampling lines are used to measure gas parameters (of the target gas) at the patient, there may be a delay due to the time it takes for the sample to enter the sampling line. For this reason, we refer to "at the time of the first and second flow rates", "at the time of the first and second gas fractions", "at the time of the first or second partial pressure" or the like. In this case, it means the time at which the gas flows of the first and second flow rates reach the patient (including sampling lines, if necessary). If the delay of the flow/gas ratio change in the gas flow path is not significant, the gas parameter is measured at approximately the same time as the flow/gas ratio change in the patient. However, if there is a delay in the flow/gas ratio change propagating in the gas path, the measurement at the patient will be at the breathing device 10 to take into account the time for the new flow/gas ratio to reach the patient. It may occur some time after the flow/gas ratio change has occurred (ie, after a delay). This delay may be ascertained and/or implemented in any suitable manner, such as by experimentation, modeling, measurement, calculation, or the like. As used herein, when referring to "at a time of" the time at which the change in flow/gas ratio reaches the patient due to the delay in the change in flow/gas ratio reaching the patient and/or at the device Conceptually, it should be interpreted as including any time after a change in flow/gas ratio. This remark applies to all embodiments herein.

When the target gas is _CO2 , the present invention is useful for monitoring exhaled _CO2 and/or for determining end-tidal _CO2 if the patient is provided with a high flow of gas. can be used. The _CO2 of the currently displayed trace shows the diluted measurement. If the target gas is O ₂ , the present embodiments can monitor exhaled O ₂ and/or determine the fraction of exhaled O ₂ (F _E O ₂ ). Measurement of _O2 may be used, for example, in preoxygenation of general anesthesia procedures in which the patient is preoxygenated to increase their _O2 levels prior to anesthesia-induced apnea (i.e., anesthetic-induced apnea). or during procedural sedation, during the pre-oxygenation phase before sedatives are administered, and during the sedation phase when the patient is sedated and can breathe shallowly. Useful. During the pre-oxygenation phase, _O2 from the system gas flow 11 is taken up by the patient and _FEO2 in the exhaled gas rises from the _beginning of the pre-oxygenation phase to the end of the pre-oxygenation phase. _FEO2 provides medical professionals with useful information regarding _O2 levels in a patient's blood _, especially in situations where it is impossible and/or impractical to obtain a patient's arterial blood gas measurements. can be done. The patient's _O2 level preferably rises during the pre-oxygenation phase.

The described embodiments may be applied to any other situation where it may be useful to know any end-tidal or exhaled gas fraction while the patient is receiving respiratory support. . The present invention can be used in anesthesia procedures (ie, operating rooms), ICUs, hospital wards, emergency departments, and the like.

2. General Embodiment—Varying Device Gas Flow Rates One embodiment is described with reference to the diagrams and graphs of FIG. 3A and the flow diagram of FIG. In general, determination of gas parameters is accomplished by varying the flow rate of system gas flow 11' (over time) in a known manner and is derived from knowledge of that time-varying flow rate and composite gas outflow 15'. The information is used to determine the parameters of the desired gas constituents in the actual breathing gas flow 13'. The reference number 11' is used for the changing system gas flow to distinguish it from the previously used reference number 11, which was used for the unchanged system gas flow for illustration purposes. Similarly, if the system gas flow changes, the leak gas flow 12', the breath gas flow 13', instead of the reference numerals 11, 12, 13, 15 used for the same parameters where the system gas flow does not change. , and composite outflow 15' reference numbers are used.

As shown in FIG. 3A, a time-varying device gas flow 11' is provided to the patient by respiratory device 10. As shown in FIG. This device gas flow with time-varying flow now includes at least two flow components. The first is the therapeutic flow component 31 due to what is needed by therapy. The second is time-varying, taking the therapeutic flow above and above that required by therapy (including any time variations in flow that may be required for therapy), but the device gas A signature (time-varying) flow component 32 that modifies/adjusts so as not to affect the effectiveness of the therapy provided by the flow. The two components 31, 32 are summed to provide the overall time varying device gas flow 11'. In one alternative, the device gas flow can be configured such that the variable flow rate is zero at times. The modified time-varying gas flow may be provided at all times, or optionally only during patient exhalation, to reduce any possible impact of the signature on respiratory assistance. Any control may be implemented in a controller or any other suitable device. Note that this is a description of the components of the time-varying flow rate, but not necessarily how the time-varying flow rate is achieved. It can be found in Applicant's publications, WO2015033288 or US2016/0193438, WO2016157106 or US2018/0104426, WO2017187390 or It can be accomplished in a number of ways, such as those described in US Patent Application Publication No. 16/096660. The entire contents of these are incorporated herein by reference.

As noted above, therapeutic flow can be a constant flow, but it can itself also have a time-varying flow component (i.e., a variable flow with one or more time-varying flow components in addition to the signature flow). gas flow). For example, as shown in FIG. 3B, the therapeutic flow rate 31' itself includes multiple components, including a constant (eg, bias/base) component 31A' and a time-varying component 31B', which are summed together over time. become a variable component (hereafter, references to variable flow rates mean time-varying, even if not explicitly stated, where the context permits). This can then be added to the signature flow rate (i.e. the time-varying therapeutic flow rate 31' is modified/adjusted by the signature flow rate 32) to create the device gas flow.

FIG. 3C is yet another example of a therapeutic flow rate 31'' having a time-varying flow component (this time a square wave). Also shown is the square wave signature flow rate 32'' leading to the time varying device gas flow 11 ^* .

A signature flow rate may, for example, simply comprise a flow rate that changes over time from a first flow rate to a second gas flow rate, but alternatively may be periodic (regular or irregular), non-periodic , random, non-repeating, etc., fluctuating flow rate or any other time varying flow rate. There need not be regular periodic changes (eg, constant frequency variations need not be, in fact it can be a varying frequency). Also, the amplitude need not be fixed. For example, the signature flow rate may be in the form of a square wave as shown in FIG. 3A. The signature flow rate can also be a step function, sawtooth, sinusoidal, or more complex random repeating or non-repeating function, or any other option that varies over time between at least two different flow rates. Alternatively, it can be a combination of one or more waves, such as sinusoidal waves with varying magnitudes and frequencies.

The signature flow component is added (modified/adjusted) to the therapeutic flow component to provide a varying device gas flow rate 11'. Thus, a varying flow rate means any flow rate that changes at least once over time. The flow rate of the device gas flow 11' varies, the therapeutic flow rate (which may be constant or may itself vary, thus itself comprising various flow components) and the therapeutic gas Includes a signature flow rate that provides an additional component for varying the therapeutic flow rate of flow. Preferably, the frequency of the signature flow (if repeating) or the period of time over which the signature flow changes (if non-repeating) is higher than the frequency of patient respiration and/or higher than the frequency of any variation in the therapeutic flow component. . While this is also not required, this is a description of the components of the time-varying signature flow component and not necessarily how the time-varying flow component is achieved. Any suitable device for varying the gas source to obtain a time varying flow rate with the above characteristics may be implemented. For example, the time-varying flow rate can be determined in Applicant's publications, WO2015033288 or US2016/0193438 (e.g., FIGS. 56-57), WO2016157106 or US2016/0193438. It can be achieved in a number of ways, such as those described in WO2018/0104426, WO2017187390 or US Patent Application Publication No. 16/096660. The entire contents of these are incorporated herein by reference. Specific non-limiting examples may be controllable valves and/or speed controllable motor/impeller configurations.

As an example, FIG. 3A shows a varying flow rate of a device gas flow 11 ′ that includes a therapeutically generated gas flow rate 31 and a time-varying (signature) component 32 . The time-varying signature component is a square wave function that provides a regularly repeating, periodically varying flow rate. When the leak gas flow rate 12' is added to the patient's exhaled gas flow rate 13', this creates a composite gas outflow (total flow) 15' having the signature flow rate 32 as a component. See, for example, item 32 in FIG. 3A. When measuring a gas parameter in the combined gas outflow (see example of measurement of the _CO2 fraction at the bottom of FIG. 3A), the time-varying flow rate 32 of the device gas flow 11' is the gas in the combined gas outflow 15'. parameters and become apparent in the measured values of the gas parameters.

Composite of gas outflow parameters The flow rate of the device gas flow 11' combined with the measured values of the parameters of the gas components of the gas outflow 15' over time is:
It can be used to determine a) the effect of system gas flow on parameters of the puffer gas flow 13' and/or b) to determine gas parameters of the actual puff patient gas flow 13'.

This determination of a) and/or b) consists of filtering, interpolating or extrapolating the composite gas outflow 15' to obtain the gas flow parameters of the call flow, the gas flow from the composite gas outflow 15'. By any suitable means such as modeling the flow parameters, calculating or otherwise determining the gas flow parameters from the composite gas outflow. Providing a signature flow rate 32 to vary the system gas flow rate 11' changes the gas fraction (or other parameter measured) in the composite gas outflow 15', and the effect of the change in the gas fraction is shown. , allows to be removed directly or indirectly from the base expiratory gas signal (expiratory gas flow 13) in an appropriate manner. The change in gas fraction can be dilution or an increased fraction of gas. Interpolation can be used, as one example, to recover waveforms and values of exhaled gases. As another example, measurements of patient gas flow rate at two points in time and parameters of gas constituents in the composite gas outflow at the same two points in time can be used to determine parameters of gas constituents in exhalation flow. . As an example, the _CO2 ratio (e.g. fraction) in the exhalation gas flow measures the device gas flow (flow rate) at two times and the _CO2 ratio (e.g. fraction) in the combined gas outflow at the same time. can be determined by doing/knowing. This can be done repeatedly at other times as the system gas flow rates change over time. Other examples are possible. As another example, as shown in FIG. 3A, actual gas flow parameters can be extrapolated from measurements. In one alternative, the device gas flow rate can be configured such that the varying rate is zero at times. This makes decisions easier.

Apparatus and methods for accomplishing such determination of gas parameters are described with reference to FIGS. 4 and 5. FIG. This device may also be used for other embodiments described herein.

FIG. 4 shows a respiratory apparatus 10 for providing flow therapy or other treatment to a patient. The device is configured to deliver the time-varying device gas flow 11' and to determine the parameters of the desired gas composition of the exhalation gas flow 13'. The device 10 may be of an integrated or separate component based construction and is generally shown within the dashed box in FIG. In some configurations, the device may be a modular configuration of components. Accordingly, the device may be referred to as a "system," but the terms may be used interchangeably without limitation. Henceforth this will be referred to as a device, but this should not be considered limiting. The device treats patients with dyspnea and treats patients with sleep apnea, while for any suitable purpose, including pre-oxygenation during anesthesia procedures, anesthesia procedures, high flow therapy, ventilation. or otherwise where monitoring of patient respiratory quality is required.

The apparatus includes a flow source 50 for providing a high flow gas 31 such as oxygen or a mixture of oxygen and one or more other gases. Alternatively, the device may have connections for coupling to a flow source. Thus, the flow source may form part of the device, or be considered separate from the device, or even part of the flow source may form part of the device, depending on the circumstances. , part of the flow source is outside the device.

The flow source can be an in-wall supply of oxygen, a tank of oxygen 50A, a tank of other gases, and/or a high flow therapy device with a blower/flow generator 50B. FIG. 4 shows flow generator 50B, optional air inlet 50C, and optional _O2 source (such as tank or _O2 generator) 50A via isolation valve and/or regulator and/or other gas flow control 50D. Although a flow source 50 with connections is shown, this is only one option. The description from here on can refer to either embodiment. The flow source can be one or a combination of a flow generator, an _O2 source, an air source, as noted. The flow source 50 is shown as part of the device 10, but may be considered a separate component in the case of an external oxygen tank or in-wall source, in which case the device connects to such flow source. has a connection port for The flow source provides a (preferably high) flow rate of gas that can be delivered to the patient via the delivery conduit and patient interface 51 . Depending on the end use, the patient interface 51 may be a non-sealing (also referred to as "non-sealing") interface such as a nasal interface (cannula) (e.g. when used in high flow therapy) or a nasal mask, a full face mask. , or a sealed interface such as a nasal pillow (eg, when used with CPAP). Time-varying flow rate embodiments may be used with non-hermetic patient interfaces. The time-varying flow gas flow is not directed to or through an external cavity of the patient, eg, preferably through a non-sealing nasal cannula. The external cavity can introduce a low pass filter that can attenuate the time-varying flow signature. Time-varying fractionation embodiments can also be used with sealed patient interfaces. Patient interface 51 is preferably a non-sealing patient interface that, for example, helps prevent barotrauma (eg, tissue damage to the lungs or other organs of the respiratory tract due to pressure differences with respect to the atmosphere). The patient interface may be a nasal interface (cannula) having a manifold and nasal prongs, and/or a face mask, and/or a nasal pillow mask, and/or a nasal mask, and/or a tracheostomy interface, or any other suitable type. It may be a patient interface. The flow source may provide a therapeutic gas flow rate, for example, from about 0.5 liters/minute to about 375 liters/minute, or any range therein, or even a range including the upper or lower limits.

The time-varying device gas flow may have a therapeutic time-varying (eg, fluctuating) flow rate, and the controller controls the gas flow modulator to provide from about 375 liters/minute to about 0 liters/minute, or preferably , from about 240 liters/minute to about 7.5 liters/minute, or more preferably from about 120 liters/minute to about 15 liters/minute; A variable flow rate is provided having one or more frequencies from 1 Hz to about 200 Hz, preferably from about 0.1 Hz to about 6 Hz, more preferably from about 0.5 Hz to about 4 Hz, more preferably from 0.6 Hz to 3 Hz. A gas flow modulator modulates a flow source (which can be a flow generator as described above, an O2 source, ambient air, etc.) and/or a gas flow parameter (e.g., flow rate, gas ratio) or otherwise. There is the possibility of a valve or other device for varying the .

The variable flow rate may include a therapeutic flow component, wherein the therapeutic flow rate is from about 375 liters/minute to about 0 liters/minute, or from about 150 liters/minute to about 0 liters/minute, or preferably about 120 liters/minute. minutes to about 15 liters/minute, or more preferably from about 90 liters/minute to about 30 liters/minute.

The variable flow rate may include a therapeutic gas flow component, and the constant (eg, bias/base) flow component of the therapeutic gas flow is between about 0.5 liters/minute and about 25 liters/minute.

The variable flow rate may include a therapeutic flow component, wherein the therapeutic flow rate is from about 0.2 liters/minute/kilogram patient to about 2.5 liters/minute/kilogram patient, preferably about 0.25 liters/minute/kilogram patient. Patient-kilogram to about 1.75 liters/minute/patient-kilogram, more preferably about 0.3 liters/minute/patient-kilogram to about 1.25 liters/minute or about 1.5 liters/minute/patient-kilogram, more preferably From about 0.4 liters/minute/kilogram patient to about 0.8 liters/minute/kilogram patient.

One or more components of the time-varying (eg, fluctuating) gas flow may have one or more frequencies from about 0.3 Hz to about 4 Hz.

The variable flow rate may comprise at least one time-varying flow rate component, each variable flow rate being between about 0.05 liters/minute/kilogram patient and 2 liters/minute/kilogram patient, preferably about 0.05 liter/minute/kilogram patient. patient kilogram to about 0.5 liters/minute/patient kilogram, preferably about 0.12 liters/minute/patient kilogram to about 0.4 liters/minute/patient kilogram, more preferably about 0.12 liters/minute/patient kilogram to about 0.35 liters/minute/patient kilogram. Alternatively, the fluctuating flow rate may comprise at least one time-varying flow rate component, each fluctuating flow rate ranging from 0.05 liters/min/kilogram patient to 2 liters/min/kilogram patient, preferably 0.1 liter/kilogram patient. The range is from 0.2 liters/minute/kilogram patient to 0.8 liters/minute/kilogram patient, preferably from 0.2 liters/minute/kilogram patient.

The above are examples of therapeutic time-varying flow rates. A signature flow rate can also be provided, which may be lower than, the same as, or higher than the therapeutic flow rate. The frequency of the signature flow can be lower, the same, or higher than the frequency of the therapeutic flow (if time varying). In some embodiments, the signature flow has a higher frequency than the therapeutic flow.

As an example, the signature flow rate can be stepped between a first flow rate and a second flow rate, one or both of which can be within a range of approximately 0 LPM to 70 LPM. The maximum signature flow rate can be the therapeutic flow rate. The signature flow rate may be combined with (eg, added to) the therapeutic flow rate, or may form part or all of the therapeutic flow rate. That is, the therapeutic flow rate itself can be the signature flow rate. In some embodiments, signature flow rate may be related to therapeutic flow rate as a percentage. For example, the signature time-varying flow rate (adult) is
- from about 0% to about 200% of the therapeutic flux;
- about 0% to 100% of the therapeutic flux,
- about 100% to 200% of therapeutic flux, or - about 50% to 150% of therapeutic flux
and/or about 0 to 140 LPM,
・Approximately 0 to 70 LPM,
・Approximately 70 to 140 LPM,
・About 40 to 100LPM, or ・About 20 to 60LPM
is within the range of

Note also that these are not limiting flows and the signature flow can be negative, but when combined with the therapeutic flow results in a positive total flow.

In some embodiments, therapeutic flow can also serve as a signature flow. they serve two purposes.

The above are only examples, other types of time varying flow rates can be provided, and the controller controls the gas flow modulator to provide a time varying device gas flow having a time varying flow rate. The device may have knowledge of the time-varying flow rate and/or may measure the time-varying flow rate provided by, for example, flow sensors (eg, 53A, 53B).

A humidifier 52 may optionally be provided between the flow source 50 and the patient to provide humidification of the delivered gas. This may be integrated with the flow source 10 to form an integrated device 59 (see dotted line) or it may be a separate humidifier but attachable to the flow source 10 . Alternatively, humidifier 52 may be a stand-alone humidifier having a chamber and base, the humidifier being coupled to flow source 10 via a conduit or other suitable means. One or more sensors 53A, 53B, 53C, 53D, such as flow rate, oxygen fraction, or other gas fraction, total or partial pressure, humidity, temperature, or other sensors may be installed throughout the device and/or the patient. 16, on the patient 16, or in the vicinity of the patient 16. Alternatively or additionally, sensors capable of obtaining such parameters may be used. Additionally or alternatively, sensors 53A-53D may measure heart rate, oxygen saturation (eg, pulse oximeter sensor 54E), partial pressure of oxygen in blood, respiratory rate, O ₂ and/or CO ₂ in blood. There may be one or more physiological sensors for sensing a patient's physiological parameter, such as the partial pressure of . Alternatively or additionally, sensors from which such parameters can be obtained can be used. Other patient sensors may include electroencephalogram sensors, waistbands for detecting respiration, and any other suitable sensors. In some configurations, a humidifier may be optional or preferred due to the benefits of the humidified gas in helping maintain airway conditions. Humidification is preferably used in conjunction with high gas flow to enhance patient comfort, compliance, support, and/or safety. One or more of the sensors may form part of the device or may be external to the device, and the device has inputs for any external sensors.

A sensor 14 is provided for measuring gas parameters (of the target gas) of the patient composite gas outflow 15 . That is, depending on the target gas, eg, oxygen, carbon dioxide, nitrogen, helium, and/or anesthetic agents such as sevoflurane, sensors are selected for sensing gases in the combined gas outflow. The sensors may be mainstream or sidestream sensors and may be placed in proximity to the nose and/or mouth (inside the nose and/or mouth, over the nose and/or mouth, near the nose and/or mouth). Other positions are also possible. Time-varying flow rate embodiments can operate with one gas parameter sensor, for example, when one gas parameter (eg, fractional CO ₂ or fractional O ₂ ) is measured. . In time-varying flow embodiments, it is not essential to measure more than one gas parameter to obtain the target parameter (e.g., fractional CO ₂ and fractional O It is not necessary to measure ₂ ).

Output from the sensors is sent to a controller to assist in controlling the device, including, among other things, varying gas flow. Alternatively or additionally, the input can come from the user. A controller is coupled to the flow source, the humidifier, and the sensor. The controller controls these and other aspects of the device, described below. A controller can operate the flow source to provide the flow of gas to be delivered. The controller also operates the gas flow modulator (including the flow source) based on feedback from the sensor, or optionally without feedback (e.g., using default settings), to control the flow provided by the flow source. , pressure, volume, and/or other parameters of the gas can be controlled. The controller may also control any other suitable parameters of the flow source to meet oxygenation requirements and/or for _CO2 removal. Controller 19 may also control humidifier 52 based on feedback from sensors 53A-53D,14. Using input from the sensors, the controller determines the oxygenation requirements and instructs the medical professional (e.g. flow rate, _O2 fraction, humidity, etc.) to coordinate the components of the respirator to provide the desired therapy. Information can be provided to a person who can control the system, and/or parameters of the flow source, gas flow modulator, and/or humidifier can be controlled as needed. Alternatively, embodiments may be used as a stand-alone monitoring device independent of the respiratory device to communicate with and control components of the respiratory device to provide information to a medical professional and/or to provide desired therapy. can be provided. A medical professional can then control the respiratory device to provide the desired therapy. Thus, the controller may not necessarily determine the oxygenation requirements and control the parameters of the device.

The controller 19 is also configured to operate the device such that the device gas flow has a time-varying flow rate that provides therapy and also a signature flow rate as described. Controller 19 may do this by any suitable means, such as controlled flow generator 50B or any other suitable gas modulator. Gas modulators may be used to modulate (ie, change, modify, adjust, or otherwise control parameters of gas flow). Each gas flow modulator may be provided within the flow source, after the flow source and before the humidifier, after the humidifier, and/or any other suitable location within the device to modulate the gas flow path. (and the flow source itself may be a gas flow modulator). The controller also operates the gas flow modulator (including the flow source) based on feedback from the sensor, or optionally without feedback (e.g., using default settings), to control the flow provided by the flow source. , pressure, volume, and/or other parameters of the gas can be controlled. The controller can also control any other suitable parameters of the flow source to meet the oxygenation requirements. The gas modulator can be, for example, those described in WO2017/187390 or US Patent Application Publication No. 16/096660, the entire contents of which are incorporated herein by reference.

The controller can then measure the composite gas outflow and determine gas parameters using any of the following techniques.

With respect to other embodiments below relating to varying gas ratios, the controller 19 may additionally or alternatively allow the device gas flow to provide a time-varying gas ratio ( _O2 or other gas fractions and/or _O2 partial pressures or other gas partial pressures), and also to have signature gas ratios (such as gas fractions and/or gas partial pressures). is configured to Controller 19 may do this by any suitable means such as controlling a proportional valve coupled to _O2 source 50A previously described in other patents or any other means. The controller can then measure the composite gas outflow and/or determine the gas parameter (eg, obtain an estimate of the gas parameter) using any of the following techniques. In one embodiment, there are two proportional valves operating 180 degrees out of phase. When one opens, the other closes. One controls the O2 fraction in the device gas flow and the other controls the air fraction in the gas flow, both keeping the total gas flow constant. In another alternative, a single proportional valve is used with the impeller, the proportional valve controlling the _O2 fraction and the impeller controlling the flow rate. In some embodiments, a single proportional valve may be used before or after the impeller. When a single proportional valve is used in front of the impeller, the proportional valve controls the _O2 fraction entering the impeller inlet along with the ambient air. In some embodiments, more than one proportional valve may be used with the impeller and may be positioned anywhere within the system relative to the impeller. The controller 19 can control the proportional valves to operate as needed to achieve the time varying gas ratios as described herein.

An input/output interface 54 (such as a display and/or input device) is provided. The input device can be any device that may be controlled from the user (e.g., clinician or patient) by, for example, oxygenation requirements, anesthetic gas medication, sensing, flow rate, gas fraction, partial pressure, and/or device. to receive information that can be used to determine other parameters of

The device also controls general anesthesia (i.e., pre-anesthetic oxygen requirements during the pre-oxygenation phase and/or intra-anesthetic oxygen requirements, including when the patient is apnea or when the patient is breathing). may be manipulated to determine the patient's dose/oxygenation requirements (hereinafter "oxygen requirements") for/related to, and after such procedures, which may include extubation periods. The device 10 also regulates the high flow gas parameters (pressure, flow, gas volume, gas composition, etc.). The device also includes a display, which may be part of the input/output, for displaying gas parameter measurements of the exhalation gas flow as a graph, digital display, or any other suitable means.

FIG. 5 illustrates a method of operating respiratory apparatus 10 having sensor 14 and controller 19 as described above. The following steps may be performed. A time-varying device gas flow 11' containing a time-varying flow rate with a signature is generated and provided to the patient. In one variation, the time-varying flow includes at least therapeutic flow component 31 . The therapeutic gas flow rate varies over time to provide a time-varying flow rate having at least a second flow rate (at a later time, e.g., 11b') that differs from the first flow rate (at an earlier time, e.g., 11a'). is modified/adjusted (eg, in this case by adding) by a signature gas flow component 32 that produces the device gas flow 11' having . This can be a simple step change or, as noted above, a more complex time-varying flow waveform such as a square wave, sine wave, or any other wave described or contemplated herein. could be. A "modified" device gas flow 11' is provided to the patient. A first flow rate 11a' of system gas flow 11' is provided to the patient (step 40) and a second flow rate 11b' of system gas flow 11' is provided to the patient sometime later (step 42). The flow rate is preferably known or, alternatively, measured. At the same time, the respiratory apparatus 10 monitors a composite gas outflow 15', which is a combination of the leak gas flow 12' (with time-varying flow rate) and exhalation gas flow 13', over time. This involves at least measuring a first parameter (in this case the _CO2 fraction) of the first flow rate 11a' of the combined gas outflow 15' and, sometime later, relating it to the provided first flow rate 11a'. (step 41), including later measuring (step 43) the same gas parameter ( _CO2 fraction) of the composite gas outflow of the second gas flow rate 11b'.

The apparatus 10 can compensate for the delay in providing the first flow rate and the measurement of the first parameter 11a' in the composite gas outflow 15' affected by the first flow rate, e.g. For sampling, a correction of 'X' seconds may be applied.

A parameter of the composite gas outflow 15 ″ is measured at or near (“near”) the patient's mouth and/or nose using the sensor 14 . In some embodiments, only one gas parameter (the target gas parameter of interest) needs to be measured. Thereafter, the gas parameters in the exhaled gas flow 13' are measured at the (preferably known, but optionally measured) first and second gas flow rates and at the first and second time points. is determined using the obtained gas parameters (step 44). In some embodiments, the first or second flow rate is 0 L/min. In some embodiments for adults, the first flow rate and the second flow rate are about 0 L/min or greater, preferably about 20 L/min or greater than about 20 L/min, more preferably about 20 L/min to about 90 L/min. / minutes. In some embodiments for premature infants/infants/children (with body mass ranging from about 1 to about 30 kg), the therapeutic flow is a minimum of about 0.5 L/min and a maximum of about 25 L/min. , 0.4-0.8 L/min/kg. For patients under 2 kg, the maximum flow is set at 8 L/min. Variable flow is set at 0.05-2 L/min/kg, with a preferred range of 0.1-1 L/min/kg, another preferred range of 0.2-0.8 L/min/kg. .

Steps 40-44 are for determining the gas parameters of the breathing gas flow 13' over time as the device gas flow 11' varies its flow rates 11a', 11b' over time due to the changing signature 32 flow rate. can be continuously/periodically repeated (step 45). During the expiratory phase of patient breathing, parameters of the gas constituents in the combined gas outflow 15' can be measured. Although the first gas flow rate 11a' and the second gas flow rate 11b' in the device gas flow 11' may simply be used, in practice the signature gas flow 32 is continuously or at least periodically / tending to vary discontinuously, the composite gas outflow 15' may be continuously or periodically (e.g., at a sampling rate) to obtain continuous or periodic measurements of exhaled gas flow parameters. ) can be measured, which can then be displayed via a graph or display to provide a real-time measurement of exhaled gas flow parameters.

As described in the above overview, various hardware configurations and methods of operation are capable of implementing the present invention. Non-limiting examples of these are described below.

3. Exemplary Embodiment - Varying Device Gas Flow Rates One exemplary embodiment will now be described with reference to Figures 1-5 and using the apparatus and control method described above. Any control method may be implemented in a controller or any other suitable device. In this embodiment, the medical professional wishes to monitor exhaled _CO2 or _O2 or an anesthetic such as sevoflurane. Exhaled gas fraction measurements can be used by medical professionals to perform a variety of monitoring functions, including confirming that gas exchange is occurring within a patient. For example, the fraction of exhaled oxygen (F _{EO 2} ) may be measured to assess the efficacy of pre-oxygenation prior to anesthesia. The fraction of carbon dioxide exhaled (F _E CO ₂ ) is an indicator of gas exchange. F _E CO ₂ monitoring is recommended or required by several anesthesia standards. However, as noted above, monitoring FeCO2 and/or FeO2 can be difficult when the gas flow is provided to the patient, especially when the gas flow is provided at high flow rates (discussed below). Sometimes. This embodiment addresses this issue. Embodiments use a non-sealing respiratory device, for example, with a non-sealing nasal cannula.

Nasal high flow (NHF) is typically used to provide respiratory assistance through a non-sealing nasal interface (cannula) as shown in FIG. The device has a _CO2 sampler (sensor 14) such as that described in WO2018070885 or US Patent Application Publication No. 16/341767, the entire contents of which are incorporated herein by reference. may The nasal cannula includes prongs configured to be inserted into the patient's nostrils during use. The prongs are sized to provide a gap between the prongs and the walls of the patient's nostrils so that the prongs do not seal the patient's nostrils. This allows, for example, entrainment of ambient gas into the patient's airway in certain circumstances and/or allows exhaled gas to flow around the prongs and out to the ambient.

A sampler is an attachment for a nasal high-flow interface (cannula) that allows measurement of exhaled gases such as carbon dioxide. In use, exhaled gas is transported (actively or passively) through the sampling line to the measurement device. Although this is sidestream sampling, the embodiments described herein may also be implemented for mainstream sampling where the _CO2 sensor is located in the main flow path. The sampler may also be adapted to transport and/or sample other exhaled gases such as _O2 . A sampler portion that captures a portion of exhaled gas for sampling may be maneuverable between the patient's nose and mouth.

The leak gas flow 12' from the device 10 changes the gas fraction (by diluting or increasing the gas fraction) in the combined gas outflow 15'. As previously mentioned, reliable measurement of the exhaled carbon dioxide and/or oxygen fraction in exhaled gas flow 13' at high flow rates is difficult. For example, in the case of pre-oxygenation, where the fraction of inspired oxygen is typically 1, oxygen from high-flow devices provides intentionally high values, limiting the clinical usefulness of the measurements. . The fraction of exhaled oxygen determines the efficacy of preoxygenation, e.g., preoxygenation is sufficient and the fraction of oxygen in the patient's lungs to provide the desired safe apnea time in the procedure. Provides insight as to whether the level is sufficient.

Note that the following relates to safe apnea times according to WO2018/185714 or US Patent Application Publication No. 16/500329, which are incorporated herein in their entirety. Safe apnea duration is defined as the time it takes for a patient to reach a specified oxygen saturation. Typically, this oxygen saturation may be 88-90%, preferably 90-92%, but this level may vary depending on the patient and the treatment being performed. Saturation below this level drops sharply to dangerous levels (<70%, preferably <80%) on steep sections of the oxyhemoglobin dissociation curve and can present a significant risk to the patient. Alternatively, safe apnea duration is defined as the time it takes for a patient to reach a specified level of arterial CO2.

The purpose of the embodiments is to accurately measure and display the waveform and amplitude of exhaled gas in the presence of Nasal High Flow (NHF). This is done through the use of variable flow or flow that is stepped between at least two different flow rates.

The device is operated to provide a time-varying device gas flow 11' having a therapeutic flow component 31 and a signature (time-varying) flow component 32 as previously described. Preferably, this is a high flow rate (with therapeutic component) as defined and more preferably between 20 and 90 liters/minute. In this example, a constant therapeutic flow rate 31 is provided and added to a square wave signature flow component 32 to produce a device gas flow 11' having a time-varying flow rate as shown in FIG. 3A. In some embodiments, signature flow component 32 can be added to constant therapeutic flow component 31 to produce device gas flow 11' having a time-varying flow rate as shown in FIG. 3A. A controller 19 or user operates the flow source 10 to provide a device gas flow 11' having a flow rate. The controller 19 may be programmed with the desired device gas flow 11' having varying flow rates, producing varying flow rates to provide the required variation in flow rates over time. Other methods of varying the flow rate are also possible, such as described in WO2018070885 or US Patent Application Publication No. 16/341767, the entire contents of which are incorporated herein by reference.

In use, the patient inhales device gas flow 11' and exhales gas flow 13'. Respiratory gas flow 13' (with _CO2 fraction) is combined with leak gas flow 12' to produce combined gas outflow 15' (with diluted _CO2 fraction) as shown in Figure 3A. do.

Sensor 14 measures the diluted _CO2 (or _O2 in other variations) fraction in the combined gas outflow and passes this information to the controller. The output of the sensor measuring the parameters of the composite gas outflow 15' is shown as the waveform 15' shown in FIG. 3A. The controller must then process that output to determine the actual _CO2 (or _O2 ) fraction in the exhaled patient gas flow.

The exhaled gas component, e.g., the fraction of _CO2 (i.e. F _E CO2 ₎ (or _O2 - i.e. F _{E O2} ), as a percentage of total gas exhaled per volume, is the time varying device gas flow can be determined from the composite gas outflow using an equation that uses knowledge of the change in flow rate of . This determination can be obtained on the assumption that fractions (components) of exhaled gas can be determined from known/measured quantities.

F _m (t), the volume fraction of gas constituents measured in the patient combined gas outflow 15 ′ from the patient at time t (which is preferably measured by the sensor 14 combined gas outflow 15 ′ of the measured _CO2 / _O2 fractionation parameters).

F _m (t) is preferably measured at the patient's mouth when the patient's mouth is open or at the nose when the patient's mouth is closed.

Q _o (t), the rate of system gas flow 11 ′ provided from the respiratory apparatus to the patient at time t (system gas flow rate).

F _m (t+Δt), the volume fraction of the measured gas constituents in the patient combined gas outflow 15′ at time t+Δt (this is the measured CO ₂ / _O2 fractionation parameters). F _m (t+Δt) is preferably measured at the patient's mouth when the patient's mouth is open or at the nose when the patient's mouth is closed.

Q _o (t+Δt), the rate of system gas flow 11 ′ provided from the respiratory apparatus to the patient at time t+Δt (system gas flow rate).

F _o (t), the volumetric fraction of the gas components in the system gas flow 11' coming from the respiratory system at times t and t+Δt.

F _o (t+Δt), the volumetric fraction of the gas component in the system gas flow 11′ coming from the respiratory system at time t+Δt.

［式中、
Ｑ_oは、装置ガスフロー１１’の流量、
Ｆ_oは、呼吸装置から来る装置ガスフロー１１’中のガス成分の体積分画、
Ｆ_Eは、呼出ガスフロー１３’（呼気ガスの体積分画）中のガス成分の体積分画、
Ｆ_mは、患者からの患者複合ガスアウトフロー１５’中のガス成分の体積分画］
を使用する。 Formula (4)

[In the formula,
Q _o is the flow rate of the device gas flow 11 ′;
F _o is the volume fraction of the gas components in the system gas flow 11' coming from the respiratory system;
_FE is the volume fraction of the gas components in the exhaled gas flow 13' (volume fraction of exhaled gas);
_Fm is the volume fraction of gas components in the patient composite gas outflow 15' from the patient]
to use.

The CO ₂ (or O ₂ ) fraction in combined gas outflow 15' is measured by sensor 14 and the flow rate of system gas outflow 11' is known (or can be measured). Therefore, by measuring the CO ₂ (or O ₂ ) fraction in the combined gas outflow 15 ′ using the sensor 14 at two (or more) different times and the CO ₂ (or O 2 ) ₂ ) by knowing/measuring the flow rate of the fractionation and system gas outflow 11' at two (or more) different times, the _CO2 (or _O2 ) fraction in the exhalation gas flow 13'; The stroke can be determined using equation (4).

のように低減される。
式（５）は、Ｆ_Eを、
Ｑ_o（ｔ），Ｑ_o（ｔ＋Δｔ），Ｆ_m（ｔ＋Δｔ），Ｆ_m（ｔ）
の関数として提供する。 Equation 4 can be simplified when measuring _CO2 or any other gas component exhaled by the patient that is not delivered to the patient by the high flow device. For measurements of CO ₂ , _Fo (t)= _Fo (t+Δt)˜0, equation (4) becomes

is reduced as
Equation (5) defines _FE as
Q _o (t), Q _o (t + Δt), F _m (t + Δt), F _m (t)
provided as a function of

In practice, the _CO2 (or _O2 ) fraction is measured continuously or periodically to obtain a real-time output, which is then the real-time _CO2 (or _O2 ) fraction of the exhaled gas flow. It can be used in combination with knowledge/measurements of the device gas flow 11', which is also continuously or periodically sampled, to determine the fractions. This can be output as a graph, digital representation, etc. on a display. In practice, the flow rate varies continuously or discontinuously over time, but periodically or regularly to provide multiple data points. Thus, the difference between the first flow rate 11a' and the second flow rate 11b' can be used by changing the flow rates at least once. Therefore, the controller measures the gas parameters at appropriate times and then calculates _FE for each measurement.

The resulting F _E CO ₂ can restore the carbon dioxide waveform seen in FIG.

4. Mathematical Derivation of Equations (4) and (5) Equations (4) and (5) are derived as follows.

［式中、
Ｑ_oは、装置ガスフロー１１’の流量、
Ｆ_oは、呼吸装置から来る装置ガスフロー１１’中のガス成分の体積分画、
ｋは、患者の口から出る装置ガスフロー１１’の比率（及び（１－ｋ）は、鼻を通る比率）、
Ｆ_Eは、呼出患者ガスフロー中のガス成分の体積分画、
Ｑ_Eは、患者の呼出ガスフローの流量］
のように表すことができる。 Assuming that all or most of the gas exhaled by the patient exits through the mouth, the volume fraction of gas (F _m ) measured as a function of time in the patient's mouth when nasal high flow is provided is:

[In the formula,
Q _o is the flow rate of the device gas flow 11 ′;
F _o is the volume fraction of the gas components in the system gas flow 11' coming from the respiratory system;
k is the ratio of the device gas flow 11' exiting the patient's mouth (and (1-k) is the ratio through the nose);
_FE is the volume fraction of gas components in the exhaled patient gas flow;
Q _E is the rate of patient exhalation gas flow]
can be expressed as

The flow is shown in FIG. 8 with reference to the patient.

Equation (1) can be rearranged to find the ratio of the unknown quantities k and _QE .

したがって、（３）から、

となり、
これをＦ_E:に関して解くと、

となる。 For two samples taken at times t and t+Δt, the time between samples, Δt, was measured during the patient's expiratory phase as the fraction of the (expired) gas components (patient composite gas outflow 15' short enough so that the volume fraction of the gas constituents F _m ), the patient exhaled gas flow rate (Q _E ), and the ratio of the device gas flow exiting the mouth (k) can be assumed to be approximately constant, Therefore, it can be approximated as

Therefore, from (3),

becomes,
Solving this with respect to F _E: yields

becomes.

This equation can be used to determine exhaled gas flow 13' parameters such as fractions of exhaled oxygen, carbon dioxide, nitrogen, helium, and/or anesthetic agents such as sevoflurane.

In some configurations, a correction or compensation can be applied to equation (4) to obtain a better estimate of the parameters (F _E ) of the gas flow components in the exhalation gas flow 13'. For example, corrections or compensations can be applied to equation (4) to account for the non-true assumption that the ratio of the combined gas outflow and the outlet device gas flow is approximately constant. Such corrections or compensations are described, for example, in Applicant's publication, WO2017187391 or US2019/0150831, the entire contents of which are incorporated herein by reference. As such, the ratio of oral flow to patient interface flow can be taken into account as a function of patient interface flow.

に低減される。 For measurements of CO ₂ , F _o (t)=F _o (t+Δt)˜0, equation (4) becomes

is reduced to

Above are the equations for oxygen and carbon dioxide in terms of known/measured quantities F _m (t), Q _o (t), F _m (t+Δt), Q _o (t+Δt). The resulting F _E CO ₂ can restore the carbon dioxide waveform seen in FIG.

In summary, but not by way of limitation, the device is operated to vary the flow (preferably within each breath) administered through a patient interface, preferably a non-sealing nasal interface (cannula). ). Doing this changes the gas fraction and allows the effects of gas fraction changes to be removed from the base expiratory gas signal. Interpolation can be used to recover waveforms and values of desired gas constituents in the patient's exhaled gas flow.

The frequency at which the flow fluctuates is configured to achieve the results of the present invention. The variation must be fast enough so that the assumptions on Q _E , k, and F _E hold, and fast enough so that interpolation can be done between samples to fully recover the waveform. Must be quick. The actual frequency required depends on the patient's breathing frequency, but is typically in the range of 1-100 Hz. The vibration frequency is preferably higher than the patient's breathing frequency or the average patient's breathing frequency (depending on whether the patient is an adult or an infant). In one embodiment, the frequency may be approximately 5 Hz. In one possible embodiment, the controller can receive input regarding the patient's breathing frequency (eg, via a sensor—directly, or indirectly, eg, via a person reading the sensor). The controller can determine the appropriate vibration frequency from that input. In another possible embodiment, the controller can receive input from the user regarding the vibration frequency based on the patient's known breathing frequency and/or the patient breathing frequency, and the controller derives the appropriate vibration frequency from that input. can decide.

Referring to FIG. 3A, if a continuous sinusoidal flow waveform is used in the device (instead of stepping between flows), this can allow for lower frequency fluctuations. In the embodiments described above, each time stage of the flow allows for the collection of data points. In sinusoidal flow embodiments, another data point may be collected by the device each time a sinusoid causes a measurable difference in _CO2 output. This fluctuating sine wave embodiment also has a good signal-to-noise ratio.

An exemplary situation for using this method relates to procedural sedation in which the patient can breathe shallowly. In this situation, the flow is stepped (eg, continuously or repetitively) over a period of time, eg, at a flow rate of about 70-40 LPM (which may look like the flow in FIG. 3A). ) can fluctuate or otherwise change. When repetitively stepped, each step flow rate is a single step change in flow rate or a continuous/discontinuous change in varying flow rates from one flow rate to another. there is a possibility. The exhaled carbon dioxide (or oxygen) fraction can then be measured in the patient's mouth during high flow therapy at about 70 LPM and then again at about 40 LPM. This measurement is repeated as the flow is continuously stepped up and down. This is a diluted measurement in the context of determining the fraction of _CO2 . The two flow rates (about 70 and about 40 LPM) and the fraction of exhaled _CO2 at these flow rates can be used in Equation 5 to calculate the fraction of undiluted exhaled _CO2 . This process is repeated over this time period and the undiluted _CO2 measurements are interpolated to represent the patient's exhaled _CO2 trace (which may look like the true waveform in FIG. 2). may be presented for illustration. This exhaled _CO2 trace, and end-tidal _CO2 values that can be inferred or determined from the exhaled _CO2 trace, are useful during procedural sedation. This is because end-tidal _CO2 values can provide an indication of _CO2 levels in patients who may be breathing shallowly and thus have higher _CO2 than expected. In this situation, a diluted waveform that only provides an indication of gas exchange does not accurately provide this indication.

5. General Embodiment—Varying Device Gas Flow Gas Fractionation An alternative embodiment using time-varying gas fractionation in the device gas flow will now be described with reference to the device described above. This is an example of a time-varying gas ratio. Any control method may be implemented in a controller or any other suitable device.

One embodiment is described with reference to the diagrams and graphs of FIG. 6A and the flow diagram of FIG. In general, parameter determination involves varying (over time) the gas fraction of the device gas flow 11'' in a known manner, knowledge of that time-varying gas fraction, and the actual breath gas flow 13''. This is accomplished by using information obtained from the composite gas outflow 15'' to determine the parameters of the desired gas composition therein. The reference number 11'' distinguishes from the previously used reference number 11, which was used for unchanged device gas flows, and the reference number 11', which was used for changing flow rate gas flows. Therefore, it is used for varying device gas flows with varying gas fractions. Similarly, if the system gas flow changes, the leak gas flow 12'', the call gas flow 13 instead of the same parameters 11, 12, 13, 15 used when the system gas flow does not change. '', and composite gas outflow 15'' reference numbers are used.

In this embodiment, the gas fraction determined is the _CO2 fraction. However, this should be used as an example only and should not be limiting. Alternatively, _O2 can be the gas fraction determined and the same approach can be taken. However, in this embodiment, if the gas fraction in the device gas flow 11'' is time-varying, it is the same type of gas that must be measured in the combined gas outflow 15''. Since _O2 (but not _CO2 ) is provided by system gas flow 11'', it is the _O2 fraction that is time-varying in system gas flow 11'' and thus combined gas outflow 15'. ' is the _O2 fraction measured. However, as the _CO2 fraction is the desired gas parameter of interest, it is derived from the measured _O2 fraction, as described below. The modified time-varying gas flow may be provided all the time or optionally only during the patient's exhalation to reduce any possible impact of the signature on respiratory assistance.

As shown in FIG. 6A, a device gas flow 11'' having a time-varying gas fraction (preferably the _O2 fraction, but may be effective with other gases provided) is delivered by the respiratory device 10 to the patient. provided to This device gas flow with time-varying gas fraction now comprises at least two gas fraction components. The first is the therapeutic gas fraction component 61 by what is needed for treatment. The second is time-varying, taking the therapeutic gas fraction above and beyond that required for therapy (including any temporal change in gas fraction that may be required for therapy), but not the device gas. It is the signature (time-varying) gas fraction 62 component that modifies/adjusts in a manner that cannot affect the effectiveness of the therapy provided by the flow. The two components are summed to provide the overall time varying device gas flow gas fraction 11''. This is an explanation of the components of the time-varying gas fractionation, but not necessarily how the time-varying gas fractionation is achieved. Any suitable apparatus can be implemented for varying the gas source to obtain a time-varying gas fraction having the properties described above.

In one embodiment, there are two proportional valves operating 180 degrees out of phase. When one opens, the other closes. One controls the _O2 fraction in the device gas flow and the other controls the air fraction in the gas flow, both keeping the total gas flow constant. In another alternative, a single proportional valve is used with the impeller, the proportional valve controlling the _O2 fraction and the impeller controlling the flow rate.

In some embodiments, a single proportional valve may be used before or after the impeller. If a single proportional valve is used in front of the impeller, the proportional valve controls the _O2 fraction entering the impeller inlet along with the ambient air. In some embodiments, more than one proportional valve may be used with the impeller and may be positioned anywhere within the system relative to the impeller. The controller 19 can control the proportional valves to operate as needed to achieve the time varying gas ratios as described herein.

As noted above, the therapeutic gas fraction may be a constant gas fraction, but the time-varying gas fraction component itself (i.e., a varying gas flow fraction with different time-varying fraction components). ). For example, as shown in FIG. 6B, the therapeutic gas fraction itself includes multiple components 31'', including a constant (eg, bias) component and a time-varying component, which are summed into a time-varying component. Become. (Hereafter, references to changing gas fractions mean time-varying, even if not explicitly stated, where the context permits). This can then be added to the signature gas fraction 62 (i.e. the time-varying therapeutic fraction 61' is modified/adjusted by the signature gas fraction 62) to create the device gas flow 11''. . The device gas flow with the time-varying gas fraction component 11'' may preferably have a non-varying flow rate.

FIG. 6C is yet another example of a therapeutic gas flow 61'' having a time-varying gas fraction component (this time a square wave). (Therapeutic gas flow can also have a time-varying fraction as shown in FIG. 3B and as described above.) Also shown is the square wave signature leading to the time-varying device gas flow 11 ^** . gas fraction 62''.

A signature gas fraction may, for example, simply comprise a gas fraction that changes over time from a first gas fraction to a second gas fraction, but alternatively may be periodic (regular or can have any kind of time-varying gas fraction, whether irregular), non-periodic, random, non-repeating, etc., fluctuating gas fraction or any other time-varying gas fraction. can. For example, the signature gas fraction may be in the form of a square wave as shown in Figure 6A. The signature gas fraction may also be a step function, sawtooth, sinusoidal, or more complex random repeating or non-repeating function, or any other option that changes over time between at least two different gas fractions. could be. A signature gas fraction component is added (modified/adjusted) to the therapeutic gas fraction component to provide a varying device gas fraction. Alternatively, it can be a combination of one or more waves, such as sinusoidal waves with varying magnitudes and frequencies. A changing gas fraction therefore means any gas fraction that changes at least once over time. The gas fraction of the device gas flow varies, the therapeutic gas fraction (which may be constant or may itself vary, and thus itself contains various gas fraction components) and A signature gas fraction is included that provides additional components for varying the therapeutic gas fraction of the therapeutic gas flow. Preferably, the frequency of the signature gas fraction (if repeating) or the period during which the frequency of the signature gas fraction changes (if non-repeating) is higher than the frequency of respiration of the patient ("breathing frequency") and/or higher than the frequency of any variation in the target gas fraction component. However, this is not required. Again, this is a description of the components of the time-varying signature gas fraction composition, but not necessarily how the time-varying gas fraction composition is achieved. This can be accomplished in a number of ways, as described above for varying flow rates.

As an example, FIG. 6A shows a changing gas fraction of a device gas flow that includes a therapeutically generated gas fraction 61 and a time-varying (signature) component 62 . The time-varying signature component is a square wave function, providing regularly repeating periodic gas fractions. When the leak gas flow 12'' is added to the patient's exhaled gas flow 13'', this creates a composite gas outflow 15'' having signature gas components 62 as components. For example, see FIG. 3A. When measuring gas parameters during the combined gas outflow (see bottom of FIG. 6A), the time-varying gas fraction of the device gas flow 11'' affects the gas parameters during the combined gas outflow 15'', It becomes apparent in the measured values of the gas parameters. In this case, the measured gas fraction in the combined gas outflow 15'' is _O2 , so the bottom graph of Figure 6A shows the _O2 fraction versus time.

The time-varying component 62 of the gas fraction of the device gas flow 11'' combined with the measured values of the parameters of the gas components of the patient composite gas outflow 15'' composite gas outflow parameter over time are:
It can be used to a) determine the effect of system gas flow on the parameters of the breathing gas flow 13'' and/or b) to determine gas parameters of the actual breathing gas flow 13''. In this case, the _O2 fraction (in this case the _O2 fraction) in the exhaled gas flow 13'' is estimated and then from there the _CO2 fraction (in this case the _CO2 gas fraction) in the exhaled gas flow 13'' ).

This determination of a) and/or b) involves filtering, interpolating, or otherwise filtering, _{interpolating} or by any suitable means such as extrapolating, modeling the gas flow parameters from the patient gas outflow 15'', calculating or otherwise determining the gas flow parameters from the composite gas outflow. be done. Providing the signature gas fraction 62 to vary the system gas flow gas fraction 11'' changes the gas fraction (or other parameter measured) in the composite gas outflow 15'', resulting in gas fraction It makes it possible to remove the influence of stroke changes directly or indirectly from the basic expiratory gas signal (expiratory gas flow 13'') in a suitable manner. Interpolation can be used, as one example, to recover waveforms and values of exhaled gases. As another example, the measured values of the device gas flow gas fraction 11'' at two times and the parameters of the gas fraction composition in the composite gas outflow 15'' at the same two times are the gas composition in the exhalation flow can be used to determine the parameters of As an example, the ratio of _O2 in the exhalation gas flow 13'' can be determined by measuring/knowing the O2 fraction in the system gas flow _O2 at two times and the _O2 fraction in the combined gas outflow at the same time. can be determined. This can be done repeatedly at other times as the device gas flow _O2 fraction changes over time. Other examples are possible. As another example, as shown in FIG. 6A, the actual gas flow parameter ( _O2 fraction) can be extrapolated from measurements. The _CO2 gas fraction in the exhaled gas flow 13'' can be determined from the _O2 fraction in the exhaled gas flow 13'' in the manner described below.

Apparatus and methods for accomplishing such determinations are described with reference to FIGS. 4 and 7. FIG. This device was described above in connection with FIG. 4 and need not be described again. However, for the sake of clarity, the device controller can operate the device to control the oxygen fraction of the device gas flow 13''. The controller does this in any suitable manner by operating the flow controller, _O2 source, air source, and any valves, motors, modulators, or other devices that may be used to control the oxygen fraction. It can be performed.

FIG. 7 illustrates a method of operating respiratory apparatus 10 having sensor 14 and controller 19 as described above. The following steps may be performed. A time-varying device gas flow 11'' containing a time-varying gas fraction with a signature (in this case the _O2 fraction) is provided to the patient. In one variation, the time-varying fraction includes at least therapeutic gas fraction (O ₂ ) component 61 . The therapeutic gas fraction changes over time to include at least a second gas fraction (at a later time, eg, 11b″) that differs from the first gas fraction (at an earlier time, eg, 11a″). ) is modified/adjusted (eg, in this case by adding) by a signature gas fraction component 62 that produces a device gas flow 11″ having a time-varying gas fraction having a . This can be a simple step change, similar to FIG. 6A, or, as above, a more complex wave such as a square wave, sine wave, or any other wave described or contemplated herein. time-varying gas fraction waveform. A "modified" device gas flow 11'' is provided to the patient. A first gas fraction 11a'' of the system gas flow 11'' is provided to the patient (step 70) and a second gas fraction 11b'' of the system gas flow 11'' is provided to the patient some time later. (Step 72). The gas fraction is preferably known or, alternatively, measured. At the same time, the respiratory apparatus 10 monitors over time a composite gas outflow 15'' that is a combination of the leak gas flow 12'' (having a time-varying gas fraction) and the exhaled gas flow 13''. This involves measuring at least a first parameter (in this case the O ₂ fraction) of the first gas fraction 11a″ of the composite gas outflow at some time, and sometime later, measuring the first gas fraction 11a″ provided. associated with the fraction 11a'' (step 71) and subsequently measuring the same gas parameter ( _O2 fraction) of the composite gas outflow 15'' of the second gas fraction 11b'' (step 73).

The apparatus 10 can compensate for the delay in providing the first gas fraction 11a'' and the measurement of the first parameter in the composite gas outflow 15'' affected by the first gas fraction. For example, for sidestream sampling, a correction of 'X' seconds may be applied.

A parameter of the combined gas outflow 15″ (O ₂ gas fraction) is measured at or near (“near”) the patient's mouth and/or nose using the sensor 14 . Only one gas parameter (the target gas parameter of interest) needs to be measured. Thereafter, the gas parameter ( _O2 fraction) in the exhalation gas flow 13'' is determined by the (preferably known, but optionally measured) first gas fraction and the second using the gas fraction (e.g. _O2 fraction) and the first and second measured gas parameters (e.g. _O2 fraction) of the combined gas outflow 15'' at the first and second time points; is determined (step 74). As described below, the _CO2 gas fraction in the breath gas flow 13'' can then be obtained from the _O2 fraction of the breath gas flow 13''.

Steps 70-74 determine the gas parameters of the exhalation gas flow 13' as the device gas flow 11'' changes its gas fractions 11a'', 11b'' over time by means of the changing signature gas fraction 62. It can be repeated continuously/periodically to obtain measurements of ( _O2 fraction) over time (step 75). During the expiratory phase of patient breathing, parameters of the gas constituents in the combined gas outflow 15'' can be measured. Although only a first gas fraction 11a'' and a second gas fraction 11b'' in the device gas flow 11'' can be used, in practice the signature gas fraction 62 is continuous over time. or at least periodically/discontinuously changing, the composite gas outflow 15'' is continuously or periodically to obtain continuous or periodic measurements of exhalation gas flow parameters. (eg, at a sampling rate), and this measurement can then be displayed via a graph or display to provide a real-time measurement of exhaled gas flow parameters.

This embodiment may be particularly useful in the described pre-oxygenation situation where the patient appears to be breathing spontaneously. Varying the oxygen fraction rather than the flow rate may be more comfortable for the patient if the patient is conscious and/or awake.

The controller may also use a phase-locked loop to synchronize the phase of the changing gas flow and the measured gas parameter.

6. Exemplary Embodiment-Varying Apparatus Gas Flow Gas Fraction An exemplary embodiment will now be described with reference to the figures and using the apparatus and control method described above. As with the varying device gas flow rate embodiment, in this embodiment the medical professional wishes to monitor exhaled anesthetic agents such as _CO2 , _O2 , nitrogen, helium, and/or sevoflurane. . The description of the purpose and construction of the device according to its embodiment (exemplary embodiment-varying device gas flow rates) applies here as well. This embodiment uses flow rates without time-varying signatures. The flow rate may be a set flow rate that does not change. Any control method may be implemented in a controller or any other suitable device.

For exemplary purposes, the gas fractions determined are _O2 and/or _CO2 fractions. However, this should be used as an example only and should not be limiting. Alternatively, other gases such as nitrogen, helium, and/or anesthetics such as sevoflurane can be target gases. In such cases, another suitable sensor for detecting the target gas in the combined gas outflow is used, i.e. suitable sensors for detecting nitrogen, helium, and/or anesthetics such as sevoflurane, etc. be.

In a first step, the _O2 gas fraction in the exhalation gas flow is determined. Then, in a second optional step, the _CO2 gas fraction in the breath gas flow can then also be determined from the _O2 gas fraction in the breath gas flow. However, in this embodiment, if the gas fractions in the device gas flow 11'' are time-varying, it is the same type of gas that is measured in the composite gas outflow 15''. Therefore, since _O2 (but not _CO2 ) is provided by system gas flow 11'', it is the _O2 fraction that is time-varying in system gas flow 11'', and thus the combined gas outflow It is the _O2 fraction that is measured in 15''. The _CO2 fraction can then be obtained from the measured _O2 fraction, as described below.

The device has a device gas flow 11'' with a time-varying gas fraction ( _O2 gas fraction) having a therapeutic gas fraction component 61 and a signature (time-varying) gas fraction component 62, as previously described. manipulated to provide In this example, a constant therapeutic gas fraction 61 is provided and added to a square wave signature gas fraction component 62 to produce a device gas flow 11'' having a time-varying gas fraction as shown in FIG. 6A. do. In some embodiments, signature gas fraction component 62 is added to constant therapeutic gas fraction component 61 to produce device gas flow 11'' having a time-varying gas fraction as shown in FIG. 6A. can do. A controller 19 or user operates the flow source 10 to provide a system gas flow 11'' having a gas fraction. The controller 19 may be programmed with the desired device gas flow 11'' having varying gas fractions, and the varying gas fractions to provide the required variation in gas fraction over time. to generate

In use, the patient inhales device gas flow 11'' and exhales gas flow 13''. The breath gas flow 13'' is combined with the leak gas flow 12'' to produce a combined gas outflow 15'' as shown in FIG. 6A. The final graph showing F _E O ₂ is for the expiratory phase.

Sensor 14 measures the O ₂ fraction in combined gas outflow 15 ″ and passes this information to controller 19 . The output of the sensor 14 measuring the parameters of the composite gas outflow 15'' is shown as the waveform 15'' shown in FIG. 6A (showing the gas fraction during exhalation). The controller must then process its output to determine the actual _O2 fraction in the exhaled patient gas flow 13''. From this, the actual _CO2 fraction of the exhaled gas flow 13'' can then be obtained.

The fraction of the exhaled gas component, e.g. _O2 , as a percentage of the total gas exhaled per volume is calculated using the formula with knowledge of the change in the gas fraction of the time-varying device gas flow, the composite gas outflow 15''. This determination can be obtained on the assumption that fractions (components) of exhaled gas can be determined from known/measured quantities.
F _m (t), the volume fraction of gas constituents measured in the patient combined gas outflow 15 ′ from the patient at time t (which is preferably measured by the sensor 14 combined gas outflow 15 ′ of the measured _CO2 / _O2 fractionation parameters).
F _m (t) is preferably measured at the patient's mouth when the patient's mouth is open and/or at the nose when the patient's mouth is closed.
F _o (t), the gas fraction of the system gas flow 11 ′ provided from the respiratory system to the patient at time t (system gas flow rate).
F _m (t + Δt), the volume fraction of the gas constituents measured in the patient combined gas outflow 15' at time t + ∆t (this is the measured CO ₂ / _O2 fractionation parameters). F _m (t+Δt) is preferably measured at the patient's mouth when the patient's mouth is open or at the nose when the patient's mouth is closed.
F _o (t+Δt), the gas fraction of the system gas flow 11′ provided from the respiratory apparatus to the patient at time t+Δt (system gas flow rate).
For varying gas fractions, equation (6) derived from equation (4) can be used.

をもたらす。
式（６）は、Ｆ_Eを、
Ｆ_o（ｔ），Ｆ_o（ｔ＋Δｔ），Ｆ_m（ｔ＋Δｔ），Ｆ_m（ｔ）
の関数として提供する。 If the gas fraction changes but the flow rate _Qo is constant (i.e. does not change),
Q _o (t + Δt) = Q _o (t)
and
Therefore, the flow terms cancel. This is the simplified formula

bring.
Equation (6) defines _FE as
F _o (t), F _o (t + Δt), F _m (t + Δt), F _m (t)
provided as a function of

This formula allows recovering a fraction of exhaled gas (in this case O ₂ ) in exhaled gas flow 13 .

は、分画のみが変化する場合により正確になり得ると仮定する（すなわち、フローを変化させるとこの比率は変わる可能性があるが、装置フロー中のガス分画を変化させるとこの比率は変わらないようである）
２． 装置は、希釈或いは酸素が患者に送達されるのを妨げることを回避するために、呼気中だけにＯ₂分画を変化させることができる
ことに留意されたい。 1. used to derive (4)

may be more accurate if only the fraction changes (i.e., changing the flow may change this ratio, but changing the gas fraction in the device flow does not change this ratio). seems not)
2. Note that the device can change the _O2 fraction only during exhalation to avoid diluting or preventing oxygen from being delivered to the patient.

Additionally, in a further development it is possible to determine the _CO2 gas fraction in the breath gas from the _O2 gas fraction in the breath gas flow.

Knowledge of F _E (t) for oxygen allows determination of F _E (t) for carbon dioxide as follows.

のように書き換えることができる。
これをＦ_E（ｔ）に関して再整理すると、

が得られる。
式中、ＦｍＣＯ２は、患者からの患者複合ガスアウトフロー１５’中のＣＯ２の体積分画である。
（式（８）の導出については以下の見出しを参照） Assuming F _o =0 for carbon dioxide (i.e., the fraction of carbon dioxide in the gas from the respirator is negligible), equation (3) becomes

can be rewritten as
Rearranging this with respect to F _E (t) yields

is obtained.
where FmCO2 is the volume fraction of CO2 in the patient combined gas outflow 15' from the patient.
(see heading below for derivation of equation (8))

_Thus , FeCO2 is now expressed in terms of known quantities, in that _kQo / _QE is now known from equation (3), since Fe(t) for oxygen is known. be done. Accordingly, the _CO2 fraction of the breathing gas flow 13'' can be determined from the _O2 fraction of the breathing gas flow 13''.

The _O2 fraction in the combined gas outflow 15'' is measured by the sensor 14 and the gas fraction of the system gas flow 11'' is known (or can be measured). Therefore, measuring the _O2 fraction in the combined gas outflow 15' using the sensor 14 at two (or more) different times, and measuring the device gas at two (or more) different times By knowing/measuring the gas fraction of flow 13'', using equations (6) and (8), the _O2 fraction in breath gas flow 13'', and thus the breath gas flow 13 The _CO2 fraction in '' can be determined.

In practice, the _O2 fraction is measured continuously or periodically/discontinuously to obtain a real-time output, which is then the real-time _CO2 fraction of exhalation gas flow 13''. (from _O2 ) can be used in combination with knowledge/measurements of the device gas flow 11'', which is also continuously or periodically sampled. This can be output as a graph, digital representation, etc. on a display. In practice, the gas fraction changes continuously or discontinuously over time, but periodically or regularly to provide multiple data points. Thus, by changing the gas fractions at least once, the difference between the first gas fraction 11a'' and the second gas fraction 11b'' can be used. Therefore, the controller measures the gas parameters at appropriate times and then calculates _FE for each measurement.

Some general remarks about this embodiment are as follows.
- The measured gas (i.e. the gas of interest) in the combined gas outflow 15'' is _O2 , to finally obtain a determination of the _CO2 fraction of the exhaled gas flow 13'' The time-varying parameter comprises a gas fraction, preferably _O2 The time-varying gas fraction comprises a therapeutic gas fraction component and a time-varying gas fraction component The time-varying gas fraction comprises , varies from 21% to 100%. Preferably the method is applied to a spontaneously breathing patient. The time-varying gas fraction may be applied throughout the patient's breathing cycle. Alternatively, the time-varying gas fraction is applied during the patient's expiratory phase.
- In one variation, the method includes determining whether the _O2 fraction has reached a pre-determined threshold (useful to indicate the end of the pre-oxygenation phase)
- Once the _O2 fraction for the exhalation gas flow 13'' has been determined, as an optional addition the _CO2 fraction in the exhalation gas flow 13'' may be obtained.

As above, once the _O2 fraction in the exhaled gas flow is known (determined by measuring _O2 in the combined gas outflow and using, for example, equation (6)), determine the _CO2 gas fraction can do. It is not essential to determine the _O2 gas fraction in this manner using equation (6). Rather, the _O2 gas fraction may be determined in another manner, such as by a sensor or other means for determining the _O2 gas fraction in the exhaled gas flow. Once this is done, the _CO2 gas fraction in the exhaled gas flow can be determined by equation (8).

この式のＯ₂版は、

ＣＯ₂版は、

である。
しかし、全てのｔに関してＦ_oCO2（ｔ）～０である（すなわち、高流量システムによって送達されるＣＯ₂の量はごくわずかである）ため、式（７．３）は、

に低減され、
式（７．４）イコール式（７．２）に設定すると、

が得られ、
Ｑ_o（ｔ）は打ち消されるため、式（７．５）は、

に低減され得る。
Ｆ_EO2は、上記のように式（６）を使用して求めることができるため、式（７．６）を再整理し、既知の量の観点から、Ｆｅ_CO2を求めることができる。

したがって、高流量中の酸素濃度を変化させると、式（６）によってＦｅＯ２及び（式（７．９）、（８）によって）ＦｅＣＯ２の両方を測定することが可能になる。 6.1 Derivation of Equation (8) Equation (3) is used to derive F _ECO2 from F _EO2 .

The _O2 version of this equation is

The _CO2 version is

is.
However, since _FoCO2 (t)~0 for all t (i.e., the amount of _CO2 delivered by the high flow system is negligible), equation (7.3) becomes

is reduced to
Setting equation (7.4) equal to equation (7.2) gives

is obtained,
Since Q _o (t) cancels, equation (7.5) becomes

can be reduced to
Since F _EO2 can be determined using equation (6) as above, equation (7.6) can be rearranged to determine Fe _CO2 in terms of known quantities.

Varying the oxygen concentration in the high flow therefore allows measurement of both FeO2 by equation (6) and FeCO2 (by equations (7.9), (8)).

7. Other Changes The following changes/additions are possible.
• The apparatus may be used with any gas sampling device, sidestream or mainstream sampling.
• The controller can control flow rates, fractions, partial pressures, etc. based on the information received. Either information can be received from a person via user input through a user interface rather than from sensors. Also, any changes made by the controller may be determined based on input received from the user either by the controller or via user input via the user interface.
• F _E O ₂ may also be measured in the same manner as described for measuring F _E CO ₂ but by measuring the patient's O ₂ fraction.
• The embodiment describes determining the breath gas flow gas parameter for one gas, eg _CO2 or _O2 . However, it is possible for clinicians to monitor more than one gas parameter (e.g., monitor _O2 fraction to assess pre-oxygenation and monitor _CO2 to assess respiration). In some cases, the above embodiments may be applied to determine accurate exhalation gas flow parameters for all gas parameters of interest.
• Time-varying gas fractionation embodiments can be implemented as time-varying gas partial pressure embodiments through the use of different sensors and processes. A person skilled in the art understands the relationship between gas fraction and gas partial pressure and can adapt accordingly.
- The above embodiments are merely some examples and should not be considered limiting. Generally speaking, using any method and/or apparatus that allows the parameters in the system gas flow 11 to be time-varying, based on the concepts embodied in the model above, the gas in the exhalation gas flow 13 can be Fractions can be determined. As an example,
_FE of the gas (using time-varying flow rate),
Q _o , Q _o (t+Δt), F _m (t+Δt), F _m (t)
or (using time-varying gas fractionation) the F _E of the gas as a function of
F _o (t), F _o (t + Δt), F _m (t + Δt), F _m (t)
by finding it as a function of
- Although the embodiments refer to _O2 and _CO2 , other gas parameters can also be determined using similar methods and apparatus, e.g. A sensor for sensing a target gas parameter of interest in a gas flow.

Claims (57)

A method for determining a parameter of gas present in an exhaled gas flow, comprising:
providing a patient with a device gas flow having a time-varying parameter;
measuring a parameter of the gas present in a combined gas outflow from the patient;
using the measured parameter and the time-varying parameter of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow;
A method, including A device for providing device gas flow and determining parameters of call patient gas flow, comprising:
a flow source;
a sensor for detecting a combined gas outflow;
a controller;
including
The device comprises:
providing a device gas flow having a time-varying parameter;
determining a parameter of gas present in a combined gas outflow from a patient, said combined gas outflow comprising:
including a leak gas flow from the device gas flow and an exhaled gas flow from the patient containing said gas;
An apparatus configured to determine said parameter of said gas present in said exhale gas flow using said determined gas parameter and said time-varying parameter. The time-varying parameter is
one or more of: flow rate of said device gas flow; or gas ratio; optionally, said gas ratio is
a fraction of the gas present in said device gas flow;
is the partial pressure of the gas present in the device gas flow;
3. A method or apparatus according to claim 1 or 2. The gas ratio is
gas fraction, preferably _O2 fraction, or gas partial pressure, preferably _O2 partial pressure,
4. A method or apparatus according to claim 1, 2 or 3. A method or apparatus according to any preceding claim, comprising providing said apparatus gas flow during an anesthetic procedure. A method or apparatus according to any preceding claim, wherein the device gas flow is provided through a non-sealing patient interface, preferably a non-sealing cannula. A method or apparatus according to any preceding claim, wherein the device gas flow is a high flow gas flow. A method or apparatus according to any preceding claim, further comprising humidifying the apparatus gas flow. Determining the parameter of the gas present in the exhalation gas flow using the measured parameter of the gas present in the composite gas outflow is performed using only one gas and the time-varying parameter A method or apparatus according to any one of claims 1 to 8, comprising measuring only, said time-varying parameter being flow rate. providing a patient with a device gas flow having a time-varying flow rate;
determining a parameter of the gas present in a combined gas outflow from the patient, the patient combined gas outflow comprising:
including a leak gas flow from the device gas flow and an exhalation gas flow from the patient containing said gas;
determining the parameter of the gas present in the exhalation gas flow using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow;
A method for determining a parameter of gas present in an exhalation gas flow comprising: said device gas flow having said time-varying flow rate comprises at least a first flow rate at a first time and a second flow rate at a second time;
using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow;
using the determined parameters of the gas present in the combined outflow determined at the first flow rate and at the second flow rate;
11. The method of claim 10. 11. The method of claim 10, wherein said parameter comprises a fraction of said gas component in said exhalation gas flow. The gas is
_CO2 ,
_O2 ,
nitrogen,
an anesthetic such as helium and/or sevoflurane;
and/or the sensor may detect in the combined gas outflow that:
_CO2 ,
_O2 ,
nitrogen,
configured to detect one or more anesthetic agents such as helium and/or sevoflurane;
Method or apparatus according to claims 1-12. A method according to any one of claims 10 to 13, wherein said parameter of said gas present in said composite gas outflow is determined during the inspiratory and/or expiratory phases of said patient breathing. said parameter of gas present in the exhalation gas flow is a gas fraction, and using said determined parameter and said time varying flow rate of gas present in said composite gas outflow, said gas present in said exhalation gas flow is: Determining said fraction (F _E ) of said gas to

[In the formula,
F _E (t) is the _CO2 or _O2 or other gas fraction in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of gas constituents measured in said patient combined gas outflow at time t;
Q _o (t), the rate of system gas flow provided to the patient at time t (system gas flow rate);
F _m (t+Δt), the fraction of the gas components measured in the patient combined gas outflow at time t+Δt (e.g., this is the measured CO ₂ , O ₂ , nitrogen , helium, and/or anesthetic fractionation parameters such as sevoflurane),
Q _o (t+Δt), the rate of the system gas flow provided to the patient at time t+Δt (system gas flow rate);
F _o (t), the volumetric fraction of gas components in the system gas flow 11′ coming from the respiratory system at times t and t+Δt;
F _o (t+Δt), the volume fraction of gas components in the system gas flow 11′ coming from the respiratory system at time t+Δt]
A method according to any one of claims 10 to 14, comprising using said parameter of gas present in the exhalation gas flow is a gas fraction, and using said determined parameter and said time varying flow rate of gas present in said composite gas outflow, said gas present in said exhalation gas flow is: Determining said fraction (F _E ) of said gas that is equal to said gas fraction F _E (t) is:
Q _o (t), Q _o (t + Δt), F _m (t + Δt), F _m (t)
[In the formula,
F _m (t), the volume fraction of gas constituents measured in said patient combined gas outflow 15′ from said patient at time t (which is preferably measured by sensor 14, combined gas outflow 15′ said measured CO ₂ /O ₂ fractionation parameter),
F _m (t) is preferably measured at the patient's mouth when the patient's mouth is open and/or at the nose when the patient's mouth is closed,
Q _o (t), the flow rate of the system gas flow 11 ′ provided from the respiratory apparatus to the patient at time t (system gas flow rate);
F _m (t+Δt), the volume fraction of the gas component measured in the patient combined gas outflow 15′ at time t+Δt (which is preferably the combined gas outflow measured by the sensor 14) the measured _CO2 / _O2 fraction parameter), _Fm (t+Δt), is preferably measured in the mouth of said patient,
Q _o (t+Δt), the rate of system gas flow 11′ provided from the respiratory apparatus to the patient at time t+Δt (system gas flow rate)]
A method according to any one of claims 10 to 15, comprising determining as a function of said parameter of said gas present in said exhalation gas flow is a gas fraction, said gas is preferably _CO2 , said determined parameter of said gas present in said combined gas outflow and said time Determining the gas fraction (F _E ) in the exhalation gas flow using the change flow rate comprises:

[In the formula,
F _E (t) is the _CO2 and/or _O2 concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of _CO2 measured in said combined gas outflow at time t;
Q _o (t), the rate of the system gas flow provided to the patient at time t (system gas flow rate);
F _m (t+Δt), the fraction of _CO2 measured in said combined gas outflow at time t+Δt;
Q _o (t+Δt), the rate of the system gas flow provided to the patient at time t+Δt (system gas flow rate)]
A method according to any one of claims 10 to 15, comprising using 18. Any one of claims 10-17, wherein the parameter of the gas present in the combined gas outflow from the patient is measured at or near the mouth and/or nose of the patient. the method of. A method according to any one of claims 10 to 18, wherein said first flow rate and said second flow rate are different flow rates. A method according to any one of claims 10 to 19, wherein said first flow rate and said second flow rate are high flow rates. Claim 10, wherein the first flow rate and the second flow rate are about 0 L/min or greater, preferably about 20 L/min or greater than about 20 L/min, more preferably about 20 L/min to about 90 L/min. 21. The method of any one of 1-20. 10. The time-varying flow rate is variable with a flow rate varying from about 0 L/min or more, preferably about 20 L/min or more than about 20 L/min, more preferably from about 20 L/min to about 90 L/min. 22. The method of any one of items 1 to 21. The method of any one of claims 10-22, comprising providing said device gas flow during an anesthetic procedure. A method according to any one of claims 10 to 23, wherein said device gas flow is provided through a non-sealing patient interface, preferably a non-sealing cannula. A method according to any one of claims 10 to 24, wherein the device gas flow is a high flow gas flow. The method of any one of claims 10-25, further comprising humidifying the device gas flow. Determining the parameter of the gas present in the exhalation gas flow using the measured parameter of the gas present in the composite gas outflow is performed using only one gas and the time-varying parameter 27. A method according to any one of claims 10 to 26, comprising measuring only, said time-varying parameter being flow rate. providing a patient with a device gas flow having a time-varying gas ratio (e.g., gas fraction);
determining a parameter of the gas present in a combined gas outflow from the patient, the patient combined gas outflow comprising:
including a leak gas flow from the device gas flow and an exhalation gas flow from the patient containing said gas;
using the determined parameter of the gas present in the composite gas outflow and the time-varying gas ratio (e.g., gas fraction) to determine the parameter of the gas present in the exhalation gas flow; and
A method for determining a parameter of gas present in an exhalation gas flow comprising: said device gas flow having said time-varying gas fraction includes at least a first gas fraction at a first time and a second gas fraction at a second time;
using the determined parameter of the gas present in the composite gas outflow and the time-varying gas fraction to determine the parameter of the gas present in the exhalation gas flow;
using the determined parameters of the gas present in the combined outflow determined in the first gas fraction and determined in the second gas fraction. Item 29. The method of Item 28. 29. The method of claim 28, wherein said parameter comprises a fraction of said gas component in said exhalation gas flow. The gas is
_CO2 ,
_O2 ,
nitrogen,
an anesthetic such as helium and/or sevoflurane;
A method according to any one of claims 28-30. A method according to any one of claims 28 to 31, wherein said parameter of said gas present in said composite gas outflow is determined during the inspiratory and/or expiratory phases of said patient breathing. said parameter of gas present in exhalation gas flow is gas fraction, using said determined parameter of gas present in said composite gas outflow and said time-varying gas fraction F _E (t); , determining said fraction (F _E ) of said gas present in the exhaled gas flow comprises:
F _o (t), F _o (t + Δt), F _m (t + Δt), F _m (t)
F _E (t) is the _CO2 and/or _O2 gas fraction (volume fraction of exhaled gas) in the exhaled patient gas flow at time t;
F _m (t), the fraction of _CO2 measured in said combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the fraction of _CO2 measured in said combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction)
A method according to any one of claims 28 to 32, comprising determining as a function of . Said parameter of said gas present in said exhaled gas flow is the gas fraction, said gas is preferably an anesthetic such as _CO2 , _O2 , nitrogen, helium and/or sevoflurane, said complex Determining the gas fraction (F _E ) in the exhalation gas flow using the determined parameter and the time-varying gas fraction of gas present in a gas outflow;

[In the formula,
F _E (t) is the _CO2 and/or _O2 concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
Fm(t), the measured fraction of _CO2 and/or _O2 or other gas in said combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the measured fraction of _CO2 and/or _O2 or other gas in said combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction)]
A method according to any one of claims 28 to 33, comprising using 35. Any one of claims 28-34, wherein the parameter of the gas present in the combined gas outflow from the patient is measured at or near the mouth and/or nose of the patient. the method of. A method according to any one of claims 28 to 35, wherein said first gas fraction and said second gas fraction are different gas fractions. the gas is _O2 ;
The method comprises: the determined _O2 ratio; and
_FmCO2 , k, _Qo , _QE
[In the formula,
F _mCO2 is the fraction of _CO2 measured in said patient combined gas outflow from said patient;
k is the ratio of the device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E is the expiratory gas flow rate of said patient]
A method according to any one of claims 31 to 36, further comprising determining the fraction of CO ₂ present in the exhaled gas flow using a function of . the gas is _O2 ;
The method comprises: the determined _O2 ratio; and

[In the formula,
F _mCO2 is the fraction of _CO2 measured in said patient combined gas outflow from said patient;
k is the ratio of the device gas flow out of the patient's mouth (and (1−k) is the ratio through the nose);
Q _o is the flow rate of the device gas flow;
Q _E is the expiratory gas flow rate of said patient]
determining the proportion of _CO2 present in the exhaled gas flow using
A method according to any one of claims 31-36. A device for providing a device gas flow and determining a parameter of gases present in an exhaled patient gas flow, comprising:
a flow source;
a sensor for detecting a combined gas outflow;
including a controller and
The device comprises:
providing a device gas flow having a time-varying flow rate;
determining a parameter of gas present in a composite gas outflow from the patient, the composite gas outflow comprising:
including a leak gas flow from the device gas flow and an exhaled gas flow from the patient containing said gas;
configured to determine the parameter of the gas present in the exhalation gas flow using the determined parameter and the time-varying flow rate of gas present in the composite gas outflow;
Device. 40. The apparatus of Claim 39, further comprising a humidifier for humidifying the apparatus gas flow. 41. A device according to claim 39 or 40, further comprising a non-sealing patient interface, preferably a non-sealing nasal cannula, for providing said device gas flow to the patient. Apparatus according to any one of claims 39 to 41, wherein the apparatus gas flow is a high flow gas flow. said device gas flow having said time-varying flow rate comprises at least a first flow rate at a first time and a second flow rate at a second time;
using the determined parameter and the time-varying flow rate of the gas present in the composite gas outflow to determine the parameter of the gas present in the exhalation gas flow;
Claims 39-42, comprising using the determined parameters of the gas present in the combined outflow determined at the first flow rate and determined at the second flow rate. A device according to any one of the preceding claims. 44. Apparatus according to any one of claims 39 to 43, wherein said parameter comprises a fraction of said gas component in said exhalation gas flow. The gas is
_CO2 ,
_O2 ,
nitrogen,
an anesthetic such as helium and/or sevoflurane;
and/or the sensor may detect in the combined gas outflow that:
_CO2 ,
_O2 ,
nitrogen,
45. Apparatus according to any one of claims 39 to 44, adapted to detect one or more anesthetic agents such as helium and/or sevoflurane. said parameter of gas present in the exhalation gas flow is a gas fraction, and using said determined parameter and said time-varying flow rate of gas present in said composite gas outflow, said gas present in said exhalation gas flow is: Determining said fraction (F _E ) of said gas to
Q _o (t), Q _o (t + Δt), F _m (t + Δt), F _m (t)
[In the formula,
F _E (t) is the gas component concentration in the exhaled patient gas flow (volume fraction of exhaled gas);
F _m (t), the fraction of gas constituents measured in said patient combined gas outflow at time t;
Q _o (t), the rate of the system gas flow provided to the patient at time t (system gas flow rate);
F _m (t+Δt), the fraction of the gas component measured in the patient combined gas outflow at time t+Δt (which is the measured _CO2 / _O2 fraction parameter of the combined gas outflow);
Q _o (t+Δt), the rate of the system gas flow provided to the patient at time t+Δt (system gas flow rate)]
46. Apparatus according to any one of claims 39 to 45, comprising determining as a function of . said parameter of said gas present in said exhalation gas flow is a gas fraction, said gas is preferably _CO2 , said determined parameter of said gas present in said combined gas outflow and said time Determining the gas fraction (F _E ) in the exhalation gas flow using the change flow rate comprises:

[In the formula,
F _E (t) is CO ₂ or O ₂ or other gas (volume fraction of exhaled gas) in the exhaled patient gas flow at time t;
F _m (t), the fraction of _CO2 measured in said combined gas outflow at time t;
Q _o (t), the rate of the system gas flow provided to the patient at time t (system gas flow rate);
F _m (t+Δt), the fraction of _CO2 measured in said combined gas outflow at time t+Δt;
Q _o (t+Δt), the rate of the system gas flow provided to the patient at time t+Δt (system gas flow rate)]
A device according to any one of claims 39 to 46, comprising using the 39- wherein the sensor is arranged to measure the parameter of the gas present in the combined gas outflow from the patient at or near the mouth and/or nose of the patient 48. Apparatus according to any one of clauses 47 to 47. A device for providing a device gas flow and determining a parameter of gases present in an exhaled patient gas flow, comprising:
a flow source;
a sensor for detecting a combined gas outflow;
a controller;
including
The device comprises:
providing a device gas flow having a time-varying gas ratio (e.g., gas fraction);
determining a parameter of gas present in a composite gas outflow from the patient, the composite gas outflow comprising:
including a leak gas flow from the device gas flow and an exhaled gas flow from the patient containing said gas;
using the determined parameter of the gas present in the composite gas outflow and the time-varying gas ratio (e.g., gas fraction) to determine the parameter of the gas present in the exhalation gas flow; A device configured to said device gas flow having said time-varying gas fraction includes at least a first gas fraction at a first time and a second gas fraction at a second time;
using the determined parameter of the gas present in the composite gas outflow and the time-varying gas fraction to determine the parameter of the gas present in the exhalation gas flow;
using the determined parameters of the gas present in the combined outflow determined in the first gas fraction and determined in the second gas fraction. 50. Apparatus according to Item 49. 51. Apparatus according to claim 49 or 50, wherein said parameter comprises a fraction of said gas component in said exhalation gas flow. The gas is
_CO2 ,
_O2 ,
nitrogen,
A device according to any one of claims 49 to 51, which is an anesthetic such as helium and/or sevoflurane. wherein said parameter of gas present in the exhalation gas flow is a gas fraction, and using said determined parameter and said time-varying gas fraction of gas present in said composite gas outflow, Determining the fraction (F _E ) of the gas present in the gas comprises:
F _o (t), F _o (t + Δt), F _m (t + Δt), F _m (t)
[In the formula,
F _E (t) is the gas component concentration (volume fraction of exhaled gas) in the exhaled patient gas flow at time t;
F _m (t), the fraction of gas constituents measured in said patient combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the fraction of the measured gas constituents in said patient combined gas outflow at time t+Δt (which is the measured _CO2 / _O2 fraction parameter of the combined gas outflow);
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction)]
including determining as a function of
Apparatus according to any one of claims 49-51. Said parameter of said gas present in said exhaled gas flow is the gas fraction, said gas is preferably an anesthetic such as _CO2 , _O2 , nitrogen, helium and/or sevoflurane, said complex Determining the gas fraction (F _E ) in the exhalation gas flow using the determined parameter and the time-varying gas fraction of gas present in a gas outflow;

[In the formula,
F _E (t) is CO ₂ or O ₂ or other gas (volume fraction of exhaled gas) in the exhaled patient gas flow at time t;
F _m (t), the fraction of _CO2 measured in said combined gas outflow at time t;
F _o (t), the gas fraction of the system gas flow provided to the patient at time t (system gas flow gas fraction);
F _m (t+Δt), the fraction of _CO2 measured in said combined gas outflow at time t+Δt;
F _o (t+Δt), the gas fraction of the system gas flow provided to the patient at time t+Δt (system gas flow gas fraction);
Q _o is the flow rate of the device gas flow;
_FE is the fraction of said gas in said exhaled gas flow]
54. The apparatus of any one of claims 49-53, comprising using the 49- wherein the sensor is arranged to measure the parameter of the gas present in the combined gas outflow from the patient at or near the mouth and/or nose of the patient 54. Apparatus according to any one of clauses 54 to 54. A method for determining the _O2 and/or _CO2 fraction present in an exhaled gas flow, comprising:
providing a humidified high-flow device gas flow having a time-varying flow rate to a patient through a non-sealing nasal cannula;
measuring the fraction of _O2 and/or _CO2 present in a combined gas outflow from the patient;
using the measured fraction of _O2 or the fraction of _CO2 present in the combined gas outflow and the time-varying flow rate, the fraction _O2 present in the exhalation gas flow and/or determining _CO2 ;
A method, including the sensor is the patient's mouth and nose;
sensing multiple gas flows by sensing oral or nasal gas flows;
3. Apparatus according to claim 2.

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